Add changelog and bump version for proposed 4.0.1 initial bi-weekly release

[alamb]

re #292

NOTE: This PR targets the active_release branch, NOT master

Rationale:

Begin preparing for the first bi weekly release

Changes:

1. Add changelog (see rendered version)
2. I made some manual edits to the changelog while reviewing them. I left the touchups in a separate commit
3. Update version to 4.0.1

Questions

1. Should we call this 4.1.0 (there are some "featurettes" and new APIs such as Support LargeUtf8 in sort kernel #25 and Add Builder interface for adding Arrays to record batches #210)?

Notes:

• Changelog was made using the code from Added changelog generator script and configuration. #289 (thanks @jorge!) via CHANGELOG_GITHUB_TOKEN=$ARROW_GITHUB_API_TOKEN ./change_log.sh

Verson was updated using (on a Mac):

sed -i '' -e 's/5.0.0-SNAPSHOT/4.0.1/g' `find . -name 'Cargo.toml'`

[codecov-commenter]

Codecov Report

Merging #298 (d62f26b) into active_release (3665296) will not change coverage.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           active_release     #298   +/-   ##
===============================================
  Coverage           82.49%   82.49%           
===============================================
  Files                 162      162           
  Lines               43980    43980           
===============================================
  Hits                36283    36283           
  Misses               7697     7697           

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[alamb]

Try again in #305