fix a tiptap bug when a pasted text takes the style of the first configured text style element

[ETLaurent]

Summary

When pasting content from your clipboard to our rich text editor, tiptap goes through the process of forcing your paste into appropriate markup based on your RT config. This often ends with wrapping something in a span. If the RT config has a span without a class defined this will appear as expected, but if the config does not have a plain span the span will get converted to the first available span configuration, which can be an unexpected stylization.

Acceptance criteria

• If a RT configuration has spans, ensure an unclassed span is added to the configuration.
• Do not add this unclassed span style to the Inline Styles menu
• Highlighting the unclassed span will not show classed spans as the active style. It will accurately reflect that the user has made no selection from the inline style menu.

What are the specific steps to test this change?

See ticket 5922

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

If adding a new feature without an already open issue, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[linear]

PRO-5922 [Rich-text] Pasting text with formatting often gets converted to the first inline style tag

[stuartromanek]

we don't need this now, I believe the other fix to be better