chore(releasing): automate release preperation steps (part 1)

[pront]

Summary

Full revamp of prepare.rs to match our current release process.
Example: #22445

This PR automates the following steps:

Create a new release branch from master to freeze commits
git fetch && git checkout origin/master && git checkout -b v0.<new version number> && git push -u

Create a new release preparation branch from master
git checkout -b website-prepare-v0.<new version number> && git push -u

Pin VRL to latest released version rather than main

To facilitate PR reviews, so I am going to automate more steps later.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

• Please read our Vector contributor resources.
  • make check-all is a good command to run locally. This check is
    defined here. Some of these
    checks might not be relevant to your PR. For Rust changes, at the very least you should run:
    • cargo fmt --all
    • cargo clippy --workspace --all-targets -- -D warnings
    • cargo nextest run --workspace (alternatively, you can run cargo test --all)
• If this PR introduces changes Vector dependencies (modifies Cargo.lock), please
  run dd-rust-license-tool write to regenerate the license inventory and commit the changes (if any). More details here.

References

[pront]

Note: the patch needs to be trimmed

[datadog-vectordotdev]

Datadog Report

Branch report: pront/release-prep-automation-v1
Commit report: 5b6b170
Test service: vector

✅ 0 Failed, 7 Passed, 0 Skipped, 25.52s Total Time