Add empty and disabled web terminal tab

(CE Port gitlab-ce!23509)

(This is an iteration towards #5426 (closed). The feature is already implemented in !7727 (closed), but I am breaking it out into smaller MR's to ease the review process.)

What does this MR do?

This MR creates the initial web terminal tab, which is empty and disabled for now.

It also makes the following CE changes to support this:

• Adds the class alert-tip to our css framework. Tip alerts are referenced in the GitLab design system but do not exist in our code yet.
• Update IDE right tabs to specify components. This is needed for EE to inject tabs.

Screenshot

This is the current implementation in !7727 (closed). This MR contains a stubbed iteration of this, but it is completely hidden.

What are the relevant issue numbers?

Part of #5426 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer