feat: Enhance LaTeX output tables by adding support for the stub and row groups

[rich-iannone]

This PR adds improved LaTeX rendering support for GT(rowname_col=), GT(groupname_col=), and .tab_options(row_group_as_column=). As these options heavily interact, all combinations of parameters were accounted for and checked (plus snapshot tests were added after visual verification).

Basic stub with row labels (top), Non-stub layout with row groups (bottom):

Row groups and stub (with row labels):

Two column stub layout using .tab_options(row_group_as_column=True):

One-column stub using .tab_options(row_group_as_column=True) with no row names:

Table with other structural features (title and source note):

Fixes: #783

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.60%. Comparing base (85d25f6) to head (31c3114).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
great_tables/_utils_render_latex.py	96.00%	2 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## main #784 +/- ## ========================================== + Coverage 91.58% 91.60% +0.02%  ========================================== Files 47 47 Lines 5752 5791 +39 ========================================== + Hits 5268 5305 +37  - Misses 484 486 +2 

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