ENH: Add a Series method which checks whether a Series is constant

[pedrocariellof]

• closes ENH: Add a Series method which checks whether a Series is constant #58806 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[mroeschke]

Thanks for the PR, as but the issue is still marked Needs Discussion and therefore this feature needs more discussion before proceeding with a PR. Closing but we can reopen when there is more agreement on moving forward with this feature in the issue