[WIP] Build site-packages dependencies

[ericvergnaud]

Changes

When locating import dependencies, if a package is not a known one, add package files as dependencies

Linked issues

#1202

Functionality

• added relevant user documentation
• added new CLI command
• modified existing command: databricks labs ucx ...
• added a new workflow
• modified existing workflow: ...
• added a new table
• modified existing table: ...

Tests

• manually tested
• added unit tests
• added integration tests
• verified on staging environment (screenshot attached)

[ericvergnaud]

@nfx this is ready for review but I want to do #1421 as part of this PR. (this is becoming spaghetti, I want to prevent it from getting worse)

[ericvergnaud]

@nfx I also want to do #1427 . This might become too big a PR, let me know your preference.

[ericvergnaud]

Closed in favor of #1440
I'll do #1421 in a separate PR