Allow only specific packages to be skipped during startup dependency installation

[puddly]

Proposed change

Add a --skip-pip-packages command line argument for more granular control over runtime package installation than --skip-pip.

I use the --skip-pip option because I frequently test upgraded/downgraded packages at runtime. When upgrading HA Core, I have to re-launch Core without --skip-pip, let it install updated dependencies for other integrations, manually re-install my own, and then re-launch with --skip-pip.

Example:

hass --skip-pip-packages zigpy,zha-quirks,bellows,zigpy-znp,zigpy-deconz,zigpy-zigate,zigpy-xbee

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Document --skip-pip-packages for more granular package installation control developers.home-assistant#1555

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[emontnemery]

This seems like a useful addition indeed 👍

We should explain it here though: https://developers.home-assistant.io/docs/creating_integration_manifest?_highlight=skip&_highlight=pip#custom-requirements-during-development--testing

[emontnemery]

Nice!

Can be merged when a docs PR is opened.

[frenck]

Docs PR is opened, and build failure is unrelated.

Going to merge this one in.

Thanks @puddly 👍