Prepare for 5.0.0~pre1

[azeey]

🎈 Release

Preparation for 5.0.0~pre1 release.

Comparison to 4.2.0: ignition-physics4_4.2.0...main

Needed by gazebosim/gz-sim#989

Checklist

• Asked team if this is a good time for a release
• There are no changes to be ported from the previous major version
• No PRs targeted at this major version are close to getting in
• Bumped minor for new features, patch for bug fixes
• Updated changelog
• Updated migration guide (as needed)
• Link to PR updating dependency versions in appropriate repository in ignition-release (as needed):

Note to maintainers: Remember to use Squash-Merge

[scpeters]

I've made some small adjustments to the changelog in 21c20ee

[codecov]

Codecov Report

Merging #293 (141e184) into main (049871a) will not change coverage.
The diff coverage is n/a.

❗ Current head 141e184 differs from pull request most recent head 21c20ee. Consider uploading reports for the commit 21c20ee to get more accurate results

@@           Coverage Diff           @@
##             main     #293   +/-   ##
=======================================
  Coverage   75.54%   75.54%           
=======================================
  Files         127      127           
  Lines        5655     5655           
=======================================
  Hits         4272     4272           
  Misses       1383     1383           

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