New --nested switch for alr show

[mosteo]

Shows a summary of crates found under the current directory. The purpose is to raise awareness of demos, tests, examples, etc. in the crates, but it may also come in handy to locate local crates in general.

Example in my dev folder:

$ alr show --nested
ⓘ Found 80 nested crates in /home/user/prog:
   ...
   wordle_ada/wordle=0.1.0: Wordle for the terminal
   wordlist_ada/wordlist=0.1.3: An English word list
   wordlist_ada/demo/demo=0.1.0-dev: Shiny new project
   yeison/yeison=0.1.0-dev: A JSON-like data structure using Ada 2022 features
   yeison/demo/demo=0.0.0: Shiny new project
$ cd wordlist_ada/
$ alr show --nested
ⓘ Found 1 nested crate in /home/user/prog/wordlist_ada:
   demo/demo=0.1.0-dev: Shiny new project

Automatically invoked after alr get and alr with when interactive:

$ cd /tmp
$ alr get ansiada
ⓘ Deploying ansiada=1.0.0...
ansiada=1.0.0 successfully retrieved.
ⓘ Found 1 nested crate in /tmp/ansiada_1.0.0_dc770a5a:
   demo/demo=0.1.0-dev: Ansiada demo
There are no dependencies.