feat(QChatMessage): make color support css color

[chuoke]

This PR code is inspired by the Vuetify color prop

What kind of change does this PR introduce?

• Bugfix
• Feature
• Documentation
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the dev branch (or v[X] branch)
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• It's been tested on a Cordova (iOS, Android) app
• It's been tested on an Electron app
• Any necessary documentation has been added or updated in the docs or explained in the PR's description.

If adding a new feature, the PR's description includes:

• Make the user's custom style convenient
• Ability to use colors other than the Color Palette
• Easy to use in combination with color-picker

Other information:

If you agree to accept, I will supplement the document

preview: