Xls Reader ListWorksheetInfo and New ListWorksheetDimensions

[oleibman]

PR #4687 corrected how Xls Writer generated its Dimensions records. We ignore the Dimensions record on read since it does not affect our processing in the slightest. However, the PR raises the possibility that someone might wish to see the data in the Dimensions record. (The PR did an adequate test for retrieving Dimensions data, but it is not generalizable.) To accommodate such a case, we add a new ListWorksheetDimensions function to Xls Reader, similar to ListWorksheetInfo. As luck would have it, the spreadsheet with which I tested the new function produced incorrect results for ListWorksheetInfo, which was ignoring XLS_TYPE_MULRK records. So I added the necessary code to fix ListWorksheetInfo as well.

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary