Adds published histories to grid list

[guerler]

This PR adds the published history grid to the grid list for consistency. When consolidating the masthead grid tabs, the three history grids i.e. Histories, Shared Histories and Published Histories will appear side by side.

PR also contains a bug fix for the histories manager to avoid responding with duplicate entries.

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]

Looks great, thank you!