Deprecate official support to run Renovate on Windows

[viceice]

Tell us more.

We plan to deprecate official support to run Renovate on Windows.

Steps planned now

• Disable Windows CI tests (ci: disable Windows tests #32754)
• Add a warning log message, when Renovate is run on Windows with a message pointing to this discussion.
• Gather comunity feedback
• Support running Renovate on Windows on best efforts via comunity

Later steps

• Make futher decisions.

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• Please vote with 👍 if you're ok with this deprecation
• Please vote with 👎 if you need Windows support and add a comment why you need it.