Rename UniformGrid to ImageData

[banesullivan]

Deprecate UniformGrid to rename it ImageData to be better aligned with VTK data model.

Resolves #3320

Please see #3320 for the original proposal and justification. The sooner we do this, the better.

[codecov]

Codecov Report

Merging #4518 (23bff3f) into main (77d3fa3) will decrease coverage by 0.01%.
The diff coverage is 95.45%.

@@            Coverage Diff             @@
##             main    #4518      +/-   ##
==========================================
- Coverage   95.66%   95.66%   -0.01%     
==========================================
  Files         107      107              
  Lines       21048    21060      +12     
==========================================
+ Hits        20135    20146      +11     
- Misses        913      914       +1     

[tkoyama010]

+100 for this change. As a PyVista user, I felt that the name UniformGrid was confusing.

[adeak]

Same question as with DefaultTheme applies: do we want to update the namespace test names? We'd only run into problems if we remove UniformGrid later, before restoring it as a vtkUniformGrid subclass.

[adeak]

Same question as with DefaultTheme applies: do we want to update the namespace test names? We'd only run into problems if we remove UniformGrid later, before restoring it as a vtkUniformGrid subclass.

Assuming an answer to leave it alone, in line with #4516 (comment).

Thanks @banesullivan, LGTM.