feat: support for font color

[mimai-hen]

Hi,
I've added support for font tag with attribute color in hexadecimal format (no support for other font attributes)
It can be very useful for displaying multicolor text.
I need it for my project, and waiting for your remarks / approval
Many thanks !

[mimai-hen]

Finally, as font is deprecated in HTML5, I've changed the pull request to support span tag with attribute style color in hexadecimal format (no support for other span or style attributes)

[cbeyls]

Thank you for the submission!

I agree this is an important feature because the Android OS supports it, at least partially. Before adding the feature, I want to make sure it's as efficient as possible and provides at least the same level of support as the Android implementation. I'll probably do it myself when I have time but you can already check my comments if you want to improve the code.

[cbeyls]

Sorry for the delay, I took time to think this through and do my own implementation in #15.
I made the following changes compared to your implementation:

• Text colors support is opt-in, because we want to respect the compose theme colors by default and make sure the text always contrasts properly with the background color in case of unsanitized HTML
• I added support for RRGGBB, RRGGBBAA, RGB and RGBA hex colors formats
• I added support for all CSS named colors
• I rolled my own hex color parser which is fast and allocation-free because I was not happy with the 2 implementations available in the Kotlin standard library
• I added text color support for all HTML inline tags, not just <span>. In case of <a>, I made sure the custom text colors properly override the link style color
• I noticed that link colors are not properly overridden in Compose 1.7 so I updated the minimum compose version to 1.8.0

Even if I won't merge this PR I will still credit your work in the release notes. Thank you for your contribution!

[mimai-hen]

Thank you very much @cbeyls 🙏 You're doing a great work 👍