Add -Top parameter and tree consolidation logic

[santisq]

New Features

• Added -Top parameter (alias -t) to Get-PSTree to limit the number of children displayed per directory.
  • Using -Top automatically enables -RecursiveSize and defaults -SortBy to Size when -SortBy is not bound.
  • Added validation logic to ensure -Top is only used with size-based sort modes (Size or DirectoriesFirstBySize), throwing a terminating error for incompatible combinations.
• New TreeSummary node class to represent aggregated "overflow" items when -Top is used.
• Added SummaryStyle property to TreeStyle.FileSystemStyle to allow customizable coloring for summary objects.

Changed

• Refactored tree processing to separate Data Shaping (sorting, pruning, and truncation) from .Render(), improving consistency and performance during enumeration.
• Updated and expanded documentation for Get-PSTree (especially the -Top parameter, TreeSummary output type, and usage examples).

[codecov]

Codecov Report

❌ Patch coverage is 98.46154% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.24%. Comparing base (5332472) to head (493ba79).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
src/PSTree/Extensions/ExceptionExtensions.cs	90.00%	1 Missing ⚠️
src/PSTree/Nodes/TreeBase.cs	95.45%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #66      +/-   ##
==========================================
+ Coverage   98.18%   98.24%   +0.06%     
==========================================
  Files          37       38       +1     
  Lines         825      913      +88     
  Branches      108      118      +10     
==========================================
+ Hits          810      897      +87     
- Misses          8        9       +1     
  Partials        7        7              

Flag	Coverage Δ
PS-5.1	97.79% <98.46%> (+0.11%)	⬆️
PS-7_Linux	73.61% <89.92%> (+2.11%)	⬆️
PS-7_Windows	97.56% <98.44%> (+0.26%)	⬆️

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