Prevent installing `crossbeam-channel` with `default-features="false"`

[LeoniePhiline]

Debouncers used to install crossbeam-channel, due to keeping notify's default features enabled even if their own default features were disabled.

With this change, crossbeam-channel will no longer be installed if notify-debouncer-* as well as notify are installed with default-features = false

Fixes #549

[LeoniePhiline]

Thanks for running the workflow!

I have adjusted the pull request with the following:

• Allow both macos_fsevent and macos_kqueue features to be forwarded from debouncer crates to their notify dependency.
• Forward macos_fsevent to notify by default, as is notify's default feature set.
• Adjust the README of both debouncers to mention enabling a backend of choice on MacOS if default features are disabled.
• Adjust notify-debouncer-mini's README formatting to match notify-debouncer-full's README.
• Adjust the github workflow to check debouncers with both MacOS backends forwarded as feature flags to notify.
• Align github workflow job names in regards to disabled features. (Align debouncer feature check job names with notify feature check job names.)

[LeoniePhiline]

Workflow run 643 can be cancelled. See intermediate version missing a job condition predicate.

Workflow run 644 can be run.

[0xpr03]

This will be part of #525

[LeoniePhiline]

Hi @0xpr03

Thanks for your review!

I have added an answer to your question, and in turn asked a clarifying question about your comment.