Strip quotes for al mxc urls converted to http

[Rosy-iso]

Description

Adds a quick regex totally not taken from the color hex fix that removes quotes from any mxc url that the mxcUrlToHttp function gets.

This should first of all fix uploaded banners not being visible from tuwunel, and I suspect it probably fixes a bunch more things elsewhere as well.

Fixes #

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

Checklist:

• 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