AppBar: Add support for custom branding

[vmilan]

Description

Shortcut: https://app.shortcut.com/cartoteam/story/344453/whitelabel-issue-icons-and-other-elements-are-not-respecting-the-app-bar-text-color [sc-344453]

Add basic support for colors customization in AppBar core components.

[shortcut-integration[bot]]

This pull request has been linked to Shortcut Story #344453: Whitelabel issue: icons and other elements are not respecting the app bar text color.

[github-actions[bot]]

Pull Request Test Coverage Report for Build 6575744574

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 70.721%

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Totals
Change from base Build 6535553140:	0.0%
Covered Lines:	2483
Relevant Lines:	3226

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💛 - Coveralls

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit a2dc022):

https://cartodb-fb-storybook-react-dev--pr792-feature-appbar-b-xqap4mfy.web.app

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