Add changelog and bump version for proposed 4.2.0 release

[alamb]

Which issue does this PR close?

re #292

I would like to propose a 4.2.0 Arrow release. Here is the changelog:

• 0c9e3c6 inline PrimitiveArray::value (inline PrimitiveArray::value #329) (Cherry pick inline PrimitiveArray::value to active_release #354)
• 8cc9b71 Fix filter UB and add fast path (Fix filter UB and add fast path #341) (Cherry pick Fix filter UB and add fast path to active_release #372)
• 58d53cf Add crate badges (Add crate badges #362) (Cherry pick Add crate badges to active_release #373)
• f0702df Only register Flight.proto with cargo if it exists (Only register Flight.proto with cargo if it exists #351) (Cherry pick Only register Flight.proto with cargo if it exists to active_release #374)
• 0817783 Doctests for BooleanArray. (Doctests for BooleanArray. #338) (Cherry pick Doctests for BooleanArray. to active_release #359)
• 9e15050 respect offset in utf8 and list casts (respect offset in utf8 and list casts #335) (Cherry pick respect offset in utf8 and list casts to active_release #358)
• ceeab6c fix comparison of dictionaries with different values arrays (Dictionary Comparison Uses Wrong Values Array #332) (Fix comparison of dictionaries with different values arrays (#332) #333) (Cherry pick Fix comparison of dictionaries with different values arrays (#332) to active_release #357)
• 6ef14ce fix invalid null handling in filter (fix invalid null handling in filter #296) (Cherry pick fix invalid null handling in filter to active_release #356)
• 1bdfbd9 Doctests for StringArray and LargeStringArray. (Doctests for StringArray and LargeStringArray. #330) (Cherry pick Doctests for StringArray and LargeStringArray. to active_release #355)
• 305b41e Mutablebuffer::shrink_to_fit (Mutablebuffer::shrink_to_fit #318) (Cherry pick Mutablebuffer::shrink_to_fit to active_release #344)

Please let me know if there is some other change that is critical to get into this release. I have been picking the changes to cherry-pick via my own judgement and I may have missed one

NOTE: This PR targets the active_release branch, NOT master

Rationale:

We have releases!

Changes:

1. Add changelog
2. Update version string to 4.2.0

Notes

I couldn't figure out how to get ./dev/release/update_change_log.sh do the right thing with the active_release branch -- it tried to include all tickets that had been closed (not just those closed between 4.1 and 4.2).

Thus I made a manual changelog via

git rev-list --pretty=oneline 4.1.0..apache/active_release

If anyone has any thoughts or time to make the changelog better I would appreciate some help

Notes:

Verson was updated using (on a Mac) using this command:

sed -i '' -e 's/4.1.0/4.2.0/g' `find . -name 'Cargo.toml'` parquet/README.md

[Dandandan]

This seems to be on the wrong place?

[alamb]

Good catch @Dandandan -- I missed this comment. Will update
#379