Add 2D guess bounds

[stephenworsley]

🚀 Pull Request

Closes #6097

[codecov]

Codecov Report

❌ Patch coverage is 95.58824% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.14%. Comparing base (043b0bc) to head (b6fbd51).
⚠️ Report is 34 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/iris/analysis/_grid_angles.py	95.52%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6799      +/-   ##
==========================================
+ Coverage   90.11%   90.14%   +0.02%     
==========================================
  Files          91       91              
  Lines       24912    25018     +106     
  Branches     4675     4694      +19     
==========================================
+ Hits        22449    22552     +103     
- Misses       1684     1686       +2     
- Partials      779      780       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.