enhancement : Add search feature in mod manager UI

[myplmy]

Short and concise description about my pull request:

• Add a search box for filtering the displayed list to the top-left corner of the mod manager dialog. [video demonstration]
• As part of the implementation, several methods were modified in the RT_Dialog_ListingWithTuple class.
• Note: This change currently only affects the mod manager dialog, but confirmed compatible with the event manager dialog. [video demonstration]

TODOs:

• - I confirm this PR is at its final form and will not receive more pushes to it unless modifications are required.
• - I confirm this PR has been previously tested by me and has no apparent issues.
• - I confirm this PR is complying with this project's Contribution Guidelines.
• - I confirm this PR is complying with this project's Syntax Ruleset.

Longer / More informative description about what my pull request does:

RT_Dialog_ListingWithTuple.cs

• New Feature: Search box for filtering keys
  • RT_Dialog_ListingWithTuple() accepts a new optional argument: bool searchBoxEnabled (default: false).
    If searchBoxEnabled is true, a search box will show in the top-left corner of the dialog.
  • Modified most methods related to dialog drawing (e.g., DoWindowContents(), FillMainRect()) for filtering displayed keys
  • Compatible with the event manager, but excluded from this PR.
• New Method: SetDisplayVariables()
  • This method updates display arrays (e.g., 'displayKeys', 'displayKeyOrgIndex') based on the search box input.
    If the search box is empty, it mirrors the 'Keys' array and its original indices.
    Otherwise, it sets them to the values filtered by the searchBoxInput
• Minor refactoring: Rename some variables, add comments, consolidate loops.

ModManager.cs

• Modified the code to call RT_Dialog_ListingWithTuple() with searchBoxEnabled = true.