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What kind of change does this PR introduce?

This PR adds support for git-based libraries in profiles.

What is the current behavior?

Sketch profiles do not support libraries downloaded from git.
Only libraries available on the Libraries Index or in the local storage could be included in a build made with profiles.

What is the new behavior?

Now the profiles support a third kind of library, and a git reference could be indicated in the profiles, like in the following example:

profiles:zero:fqbn:arduino:samd:arduino_zero_nativeplatforms:      -platform:arduino:samd (1.8.14)libraries:      -git:https://github.com/cmaglie/FlashStorage.git#1.0.0default_profile:zero

The specific git-revision of the library specified in the profile will be downloaded from git and cached in the data directory'sinternal folder. The downloaded copy is cached only the first time and will not be downloaded again.

If the git-reference is updated on the repository, the cached copy will become outdated, and the only way to refresh it is to delete the internal cache directory to force the Arduino CLI to download it again.

For example, a user trying to always utilize the latestmain branch of a library might be tempted to write something like:

libraries:      -git:https://github.com/cmaglie/FlashStorage.git#main

BTW, this won't work well because, after the first compile (and download from git), the Arduino CLI will never try again to refresh the library.

Does this PR introduce a breaking change, and istitled accordingly?

No

Other information

Fix#2133