Switch to rst changelogs

[Yadunund]

This is to align with REP 132 and will greatly improve the ease of updating changelogs in the future as they will be auto-populated when running catkin_generate_changelog

Note: The CHANGELOG.rst was autogenerated from the existing CHANGELOG.md using catkin_md2rst_changelog

Note: rmf_traffic_examples did not have a CHANGELOG.md so added a new .rst one.

[codecov]

Codecov Report

Merging #100 (4186b70) into main (43c76d9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #100   +/-   ##
=======================================
  Coverage   23.02%   23.02%           
=======================================
  Files         369      369           
  Lines       30769    30769           
  Branches    14371    14371           
=======================================
  Hits         7085     7085           
- Misses      14202    14234   +32     
+ Partials     9482     9450   -32     

Flag	Coverage Δ
tests	22.89% <ø> (ø)

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see 32 files with indirect coverage changes