fix(packaging/windows): Allow WiX installers to downgrade and overwrite

[ReenigneArcher]

Description

Update Windows WiX packaging to better support switching between release and PR builds. Set CPACK_WIX_PROPERTY_REINSTALLMODE to amus so MSI replaces existing files regardless of embedded file versions, and add a custom WiX template with MajorUpgrade AllowDowngrades="yes" to remove the default downgrade block.

Same as LizardByte/Sunshine#5435

Screenshot

Issues Fixed or Closed

Roadmap Issues

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

See our AI usage policy.

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.06%. Comparing base (9b03ab3) to head (381d01e).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff            @@
##           master      #57    +/-   ##
========================================
  Coverage   76.06%   76.06%            
========================================
  Files          24       24            
  Lines        7303     7303            
  Branches     2736     2736            
========================================
  Hits         5555     5555            
- Misses       1222     1483   +261     
+ Partials      526      265   -261     

Flag	Coverage Δ
Linux-Clang	57.52% <ø> (ø)
Linux-GCC	68.54% <ø> (ø)
Windows-MSVC	88.01% <ø> (ø)
Windows-MinGW-UCRT64	65.95% <ø> (ø)
macOS	51.35% <ø> (ø)

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see 11 files with indirect coverage changes

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