Fixed black dark theme, contrast issues etc

[Godmartinz]

Description

Corrects some contrast issues with the Black Dark theme

Fixes #SC-24144

Type of change

Please delete options that are not relevant.

• [ x] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Test Configuration:

• PHP version:
• MySQL version
• Webserver version
• OS version

Checklist:

• I have read the Contributing documentation available here: https://snipe-it.readme.io/docs/contributing-overview
• I have formatted this PR according to the project guidelines: https://snipe-it.readme.io/docs/contributing-overview#pull-request-guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[shortcut-integration]

This pull request has been linked to Shortcut Story #24144: Low contrast on dark skins.

[what-the-diff]

PR Summary

• Updated Main Text and Link Colors
  The color of the main text and links in the application has been modified to provide better visibility and readability.
• Augmented Search Highlight Style
  The search highlight feature has been improved to assist users in easily locating their search terms within the site.
• Removed Outdated Styling
  Certain older styles associated with links which were no longer needed have been removed to clean up the code and reduce complexity of the styling configuration.
• Enriched Component Appearance
  The color scheme for options within the 'select2' component has been updated to enhance the visual experience.
• Added Background Color for Important Tables
  Tables classified with a 'danger' status now have a distinctive background color, helping to draw attention to significant information.
• Removed Unnecessary Newline
  An unnecessary newline at the end of the file has been removed to maintain better coding standards.

[snipe]

Thanks! Can you check the other dark skins as well for similar issues?