Split Ubuntu workflow into one for x86 and one for arm

[mcbarton]

Description

Please include a summary of changes, motivation and context for this PR.

This splits the Ubuntu workflow into one for x86 and one for arm. This makes it easier to maintain, and allows us to have a build badge for both build targets.

Fixes # (issue)

Type of change

Please tick all options which are relevant.

• Bug fix
• New feature
• Requires documentation updates

Testing

Please describe the test(s) that you added and ran to verify your changes.

Checklist

• I have read the contribution guide recently

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.17%. Comparing base (d6b3bf7) to head (807751f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #480   +/-   ##
=======================================
  Coverage   71.17%   71.17%           
=======================================
  Files           9        9           
  Lines        3552     3552           
=======================================
  Hits         2528     2528           
  Misses       1024     1024