Allow for Markup in UI page title

[PApostol]

Description

A custom page title can be set on the UI with the instance_name variable in airflow.cfg. It would be nice to have the option to include Markup text in that variable for further customization of the title, similar to how dashboard alerts introduced in #18284 allow for html=True.

Use case/motivation

It would be useful to be able to use formatting like underline, bold, color, etc, in the UI title. For example, color-coded environments to minimize chances of a developer triggering a DAG in the wrong environment:

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[kaxil]

Assigned the issue to you :)