Replace markblocks with rewritten mark-blocks

[andyasp]

What this PR does

This is still a work in progress. Documentation needs to be added and there are references to markblocks that need to be replaced. This has been completed.

Replaces markblocks with a rewritten version uncreatively named mark-blocks.

The motivation for this is that I'm in a situation (don't ask) that requires marking and then later unmarking a large number of blocks.

markblocks as written was limiting for this because:

• it only supports adding marks, not removing them
• it only supports blocks specified as an argument, which doesn't work for large lists
• marking blocks can fail halfway (on the global marker) and then can't be retried without manual intervention
• when a failure is encountered on a large number of blocks it would be nice to easily resume in a way that does not replicate work or require modifying the input

The rewrite addresses these points.

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[github-actions]

💻 Deploy preview available: https://deploy-preview-mimir-10597-zb444pucvq-vp.a.run.app/docs/mimir/latest/

[tacole02]

Suggested change

	# Mark blocks tool
	# Mark-blocks tool

[andyasp]

Thank you for this and the other suggestions! I committed most of them and percolated them out the changes to other tools READMEs for consistency. These titles seem tricky though. "Mark-blocks" strikes me as off because it's like a mixture of the actual tool name and a title but neither. I changed it to mark-blocks here and then mark-blocks in the README. Does that seem okay?