DOC-2498: Added support for using raw CSS in the list of possible colours, using the `color_map_raw` property.

[kemister85]

Ticket: DOC-2557 Support: TINY-11385

Site: Release notes

Site: color_map_raw

Changes:

• Added addition, and new option for color_map_raw option.

Pre-checks:

• [x] Branch prefixed with feature/<version>/, hotfix/<version>/, staging/<version>/, or release/<version>/.
• [x] Included a release note entry for any New product features.

Review:

• [x] Documentation Team Lead has reviewed