gRPC: allow cancellation of downloads

[cmaglie]

Please check if the PR fulfills these requirements

See how to contribute

• [X] The PR has no duplicates (please search among the Pull Requests before creating one)
• [X] The PR follows our contributing guidelines
• [ ] 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?

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

[codecov[bot]]

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 :warning:
commands/instances.go	25.00%	0 Missing and 3 partials :warning:
commands/service_platform_download.go	33.33%	0 Missing and 2 partials :warning:
.../arduino/cores/packagemanager/install_uninstall.go	33.33%	0 Missing and 2 partials :warning:
commands/service_library_download.go	0.00%	0 Missing and 1 partial :warning:
internal/arduino/resources/index.go	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ 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](https://app.codecov.io/gh/arduino/arduino-cli/pull/2609/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino) | Coverage Δ | | |---|---|---| | [unit](https://app.codecov.io/gh/arduino/arduino-cli/pull/2609/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino) | `70.26% <55.17%> (-0.05%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.