[Rich text editor] Fix code appearance

[jonnyandrew]

Type of change

• Feature
• Bugfix
• Technical
• Other :

Content

Fix issue where inline code does not display with the correct background color if the system theme is different to the theme selected in the in-app settings.

Motivation and context

Fixes vector-im/verticals-internal#23

Screenshots / GIFs

Light in-app, dark system	Dark in-app, light system	Black in-app, light system

Tests

• Go to the in-app settings and enable the light theme
• Go to the system settings and enable dark mode
• (or vice-versa)
• Enable the rich text editor
• Compose code in the rich text editor
• Note the background of the code
• Send the code to the room
• Note the background of the code in the timeline

Tested devices

• Physical
• Emulator
• OS version(s): Android 13

Checklist

• Changes has been tested on an Android device or Android emulator with API 21
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/vector-im/element-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request includes a new file under ./changelog.d. See https://github.com/vector-im/element-android/blob/develop/CONTRIBUTING.md#changelog
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off
• You've made a self review of your PR
• If you have modified the screen flow, or added new screens to the application, you have updated the test UiAllScreensSanityTest.allScreensTest()

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[jmartinesp]

LGTM!