Added --config-dir flag

[cmaglie]

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• The PR has no duplicates (please search among the Pull Requests
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• The PR follows
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• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• UPGRADING.md has been updated with a migration guide (for breaking changes)
• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

Adds the --config-dir global flag that overrides the default data directory. This command can be used with config init --dest-dir to work in an "isolated" environment.

What is the current behavior?

What is the new behavior?

$ arduino-cli config init --dest-dir test --additional-urls https://arduino.esp8266.com/stable/package_esp8266com_index.json
Config file written to: /home/cmaglie/test/arduino-cli.yaml
$ cat test/arduino-cli.yaml 
board_manager:
    additional_urls:
        - https://arduino.esp8266.com/stable/package_esp8266com_index.json
$ arduino-cli core update-index --config-dir test/
Downloading index: library_index.tar.bz2 downloaded                                                                                                                                    
Downloading index: package_index.tar.bz2 downloaded                                                                                                                                    
Downloading index: package_esp8266com_index.json downloaded                                                                                                                            
Downloading missing tool builtin:serial-discovery@1.4.1...
builtin:serial-discovery@1.4.1 downloaded                                                                                                                                              
Installing builtin:serial-discovery@1.4.1...
Skipping tool configuration....
builtin:serial-discovery@1.4.1 installed
Downloading missing tool builtin:serial-monitor@0.14.1...
builtin:serial-monitor@0.14.1 downloaded                                                                                                                                               
Installing builtin:serial-monitor@0.14.1...
Skipping tool configuration....
builtin:serial-monitor@0.14.1 installed
Downloading missing tool builtin:ctags@5.8-arduino11...
builtin:ctags@5.8-arduino11 downloaded                                                                                                                                                 
Installing builtin:ctags@5.8-arduino11...
Skipping tool configuration....
builtin:ctags@5.8-arduino11 installed
Downloading missing tool builtin:dfu-discovery@0.1.2...
builtin:dfu-discovery@0.1.2 downloaded                                                                                                                                                 
Installing builtin:dfu-discovery@0.1.2...
Skipping tool configuration....
builtin:dfu-discovery@0.1.2 installed
Downloading missing tool builtin:mdns-discovery@1.0.9...
builtin:mdns-discovery@1.0.9 downloaded                                                                                                                                                
Installing builtin:mdns-discovery@1.0.9...
Skipping tool configuration....
builtin:mdns-discovery@1.0.9 installed
Sto scaricando l'indice: package_index.tar.bz2 scaricato                                                                                                                               
Sto scaricando l'indice: package_esp8266com_index.json scaricato                                                                                                                       
$ ls -l test/
totale 40320
-rw-r--r-- 1 cmaglie cmaglie      111 lug 30 20:43 arduino-cli.yaml
-rw-r--r-- 1 cmaglie cmaglie      108 lug 30 20:43 inventory.yaml
-rw-r--r-- 1 cmaglie cmaglie 40052066 lug 30 20:43 library_index.json
-rw-r--r-- 1 cmaglie cmaglie      566 lug 30 20:43 library_index.json.sig
-rw-r--r-- 1 cmaglie cmaglie   181534 lug 30 20:43 package_esp8266com_index.json
-rw-r--r-- 1 cmaglie cmaglie  1012551 lug 30 20:43 package_index.json
-rw-r--r-- 1 cmaglie cmaglie      566 lug 30 20:43 package_index.json.sig
drwxr-xr-x 3 cmaglie cmaglie     4096 lug 30 20:43 packages
drwxr-xr-x 3 cmaglie cmaglie     4096 lug 30 20:43 staging
drwxr-xr-x 2 cmaglie cmaglie     4096 lug 30 20:43 tmp
$ 

Does this PR introduce a breaking change, and is titled accordingly?

Other information

Fix #2533
cc @pillo79

[codecov]

Codecov Report

Attention: Patch coverage is 88.46154% with 3 lines in your changes missing coverage. Please review.

Project coverage is 70.25%. Comparing base (b8c927b) to head (535e1da).
Report is 2 commits behind head on master.

Files	Patch %	Lines
internal/cli/configuration/configuration.go	81.25%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2677      +/-   ##
==========================================
+ Coverage   70.22%   70.25%   +0.02%     
==========================================
  Files         222      222              
  Lines       21348    21365      +17     
==========================================
+ Hits        14992    15010      +18     
+ Misses       5177     5176       -1     
  Partials     1179     1179              

Flag	Coverage Δ
unit	70.25% <88.46%> (+0.02%)	⬆️

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[pillo79]

Thank you for this! 🚀
I think the use case that allows to easily do sandbox tests should also be mentioned in the documentation, but I'm not sure how to make that happen 🙂

[cmaglie]

Thank you for this! 🚀 I think the use case that allows to easily do sandbox tests should also be mentioned in the documentation, but I'm not sure how to make that happen 🙂

Just open a PR with the desired changes in docs/... 😃