freedesktop.org/icon theme

[and-ri]

closed #630

[what-the-diff]

PR Summary

• New file added
  A new file has been introduced in the project
• URL update for distributable and versions
  Switched the URL to point to freedesktop.org/icon-theme rather than github.com/freedesktop/hicolor-icon-theme
• Build dependencies, script, and env variables updated
  Improvements have been made to the configure command line arguments pertaining to build dependencies, scripts, and environment variables
• Theme existence test in share folder
  Enabled a test to ensure the index theme is present in the share folder (exit code 0 indicates success)