feat(linux): unifiy display_name handling among linux capture backends

[Kishi85]

Description

Linux capture methods currently handle display_names differently for each type of capture backend:

• portalgrab/kmsgrab/wlgrab: Preferred display_name is the display connector name (e.g. HDMI-A-1, DP-2) as those are unique and stable per system (e.g. connecting another monitor does not change the designation of an existing screen).
• kmsgrab/x11grab: Use only an index-based display_name that is not necessarily in a stable order.

Display names can be used for the output_name (Display Id) configuration option which currently is rather confusing due to the different handling.

To reduce confusion and unify handling this PR adds connector-based display_names for kmsgrab and x11grab (while maintaining backwards compatibility) and also updates available documentation to reflect the correct options for the output_name configuration setting on Linux in general and specifics per capture backend.

Screenshot

Issues Fixed or Closed

• Resolves Misleading Label/Help Text when specifying default display under Configuration>Audio/Video tabs. #5154
• Resolves Changing display id not working anymore #5231

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 failed

Failed conditions
7 New issues
7 New Code Smells (required ≤ 0)

See analysis details on SonarQube Cloud

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