ci: Local bin/relock flow with mise

[sl0thentr0py]

• list all required rubies in .mise.toml and install with mise install
  • leave note in CONTRIBUTING.md for ruby 3.0 patch needed on latest macos
• add a bin/relock script
  • ./bin/relock: regenerate all lockfiles
  • ./bin/relock -l: list all cells in matrix
  • ./bin/relock --cell <cell>: regenerate lockfile for single cell
  • ./bin/relock --gem <gem>: regenerate lockfiles for one gem
• use bin/relock in update-lockfiles.yml workflow
  • add summary of changed gems in PR description
• split devcontainer latest pin to a separate MISE_ENV

Issues

• part of: Acknowledge dependency pinning audit for sentry-ruby #2961
• part of: RUBY-180

[linear-code]

RUBY-180

[cursor]

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[dingsdax]

Don't think this is used.