Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• 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)

• What kind of change does this PR introduce?

Enhances an existing command.

• What is the current behavior?

Calling lib install with --zip-file or --git-url doesn't check if the used zip or git repository contain a valid library.

This affects also the gRPC interface.

• What is the new behavior?

Calling lib install with --zip-file or --git-url now checks if the used zip or git repository contain a valid library and fails if it not.

A valid library must contain an header file with the same name as the library and a library.properties file as documented.
https://arduino.github.io/arduino-cli/latest/library-specification

This affects also the gRPC interface.

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

Nope.

• Other information:

None.

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