docs: Update architecture with recent watcher changes

[radeksimko]

I plan to update the diagrams once the remaining changes are finished as part of the following issues

• decoder: Pick core schema only based on required_version constraint #993
• terraform/module: Introduce new job to parse provider versions from lock file #992
• terraform/module: Avoid running a job if nothing has changed #1002

as otherwise it would need to be updated again.

[github-actions]

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