Introduce vertical split mode for executors

[ilyachur]

Introduce 2 new options:

• g:cmake_build_executor_split_mode - allows to change default mode and open CMake windows in vertical mode. (Available values: 'sp' - horizontal mode, 'vsp' - vertical mode).
• g:cmake_build_executor_window_size - replaces the variable g:cmake_build_executor_height defines the size of executor window.

Option g:cmake_build_executor_height was deprecated and will be removed at the end of April 2024.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (79692cf) 98.5% compared to head (88dd3fb) 98.5%.

Additional details and impacted files

@@          Coverage Diff           @@
##           master    #197   +/-   ##
======================================
  Coverage    98.5%   98.5%           
======================================
  Files          19      19           
  Lines        1283    1291    +8     
======================================
+ Hits         1264    1272    +8     
  Misses         19      19           

Files	Coverage Δ
autoload/cmake4vim.vim	99.5% <100.0%> (+<0.1%)	⬆️
autoload/utils/common.vim	98.7% <100.0%> (+0.1%)	⬆️
autoload/utils/exec/job.vim	98.6% <100.0%> (ø)
autoload/utils/exec/system.vim	100.0% <100.0%> (ø)
autoload/utils/exec/term.vim	98.3% <100.0%> (+<0.1%)	⬆️
autoload/utils/window.vim	98.2% <100.0%> (ø)

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