misc: Use media types instead of patterns

[TheEvilSkeleton]

Description

This adds a media type for .exe files.

• Related to [Request]: Only show .exe and .msi files when opening file dialog #2466
• Closes [Bug]: File picker only shows MSIs on default filter #2555

Type of change

• 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
• Misc

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.
Provide instructions so we can reproduce.

• Locally

[TheEvilSkeleton]

Blocking this MR, as we agreed on solely fixing bugs.

[TheEvilSkeleton]

I'm unblocking this because we're polishing the UI and UX too.

[github-actions]

Pylint result on modfied files:

------------- Module bottles.frontend.utils.filters
bottles/frontend/utils/filters.py:17:0: E0401: Unable to import 'gi.repository' (import-error)
bottles/frontend/utils/filters.py:20:4: W0622: Redefining built-in 'filter' (redefined-builtin)
bottles/frontend/utils/filters.py:21:20: E0602: Undefined variable '_' (undefined-variable)
bottles/frontend/utils/filters.py:28:4: W0622: Redefining built-in 'filter' (redefined-builtin)
bottles/frontend/utils/filters.py:35:4: W0622: Redefining built-in 'filter' (redefined-builtin)
bottles/frontend/utils/filters.py:36:20: E0602: Undefined variable '_' (undefined-variable)
bottles/frontend/utils/filters.py:19:0: W0612: Unused variable 'add_executable_filters' (unused-variable)
bottles/frontend/utils/filters.py:27:0: W0612: Unused variable 'add_yaml_filters' (unused-variable)
bottles/frontend/utils/filters.py:34:0: W0612: Unused variable 'add_all_filters' (unused-variable)

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