Pagination fixes

[ricellis]

PR summary

Various fixes for pagination

Fixes: s1189

Note: An existing issue is required before opening a PR.

PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the
  Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

What is the current behavior?

The new pagination feature code (unreleased) from #819 had a few bugs.

• Wrong error message raised for consumed vs mixed state on pager
• key option was allowed for view-like pagers
• skip option set by user was not removed from subsequent pages

What is the new behavior?

• Correct Pager state error message strings
• Disallow key as an option for pagination
• Remove skip option from subsequent pages
• Update assertions in Pager state tests to ensure the correct message
• Add new tests for key option validation
• Add new tests for asserting skip option changes
• Fix default operation in bookmark test

Does this PR introduce a breaking change?

• Yes
• No

Other information