gRPC: allow cancellation of downloads

[cmaglie]

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• Tests for the changes have been added (for bug fixes / features)
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• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

Allows the cancellation of a gRPC call involving a download.

What is the current behavior?

If a gRPC call is blocked in a slow download, it cannot be interrupted. Even if the gRPC call is canceled, the download will continue in the background.

What is the new behavior?

Closing a gRPC call will terminate the download process immediately.

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

No

Other information

Fix #2595

[umbynos]

LGTM

[codecov]

Codecov Report

Attention: Patch coverage is 55.17241% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 70.26%. Comparing base (ba19a2d) to head (66a4f27).

Files	Patch %	Lines
internal/arduino/cores/packagemanager/profiles.go	33.33%	0 Missing and 4 partials ⚠️
commands/instances.go	25.00%	0 Missing and 3 partials ⚠️
commands/service_platform_download.go	33.33%	0 Missing and 2 partials ⚠️
.../arduino/cores/packagemanager/install_uninstall.go	33.33%	0 Missing and 2 partials ⚠️
commands/service_library_download.go	0.00%	0 Missing and 1 partial ⚠️
internal/arduino/resources/index.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2609      +/-   ##
==========================================
- Coverage   70.30%   70.26%   -0.05%     
==========================================
  Files         222      222              
  Lines       21262    21262              
==========================================
- Hits        14948    14939       -9     
- Misses       5131     5147      +16     
+ Partials     1183     1176       -7     

Flag	Coverage Δ
unit	70.26% <55.17%> (-0.05%)	⬇️

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