Add message to Invocations panel for no invocations

[ahmedhamidawan]

This adds a message for no invocations to display:

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[ahmedhamidawan]

Move the Go-to-all button at the top of ActivityPanel? (Not in this PR):

... Could we get the full invocation list button at the top of the panel ...

Originally posted by @mvdbeek in #18137 (comment)
Can also include this here if needed? (not included in this PR):

Before	After

[jdavcs]

Looks good, thanks!