Convert difftool to use workflow panel

[na9da]

What this PR does

• Fixes Convert Diff tool to workflow #7457
• Removes showCloseButton option for Tool. This was no longer being used after New version of Map Navigation #5062
• Removes CloseToolButton component which showed a close button in the map toolbar. This was only being used by the difftool which no longer requires it after the switch to workflow panel.

Previously diff tool used a floating side panel design which was introduced before we had WorkflowPanel. This PR updates the difftool to use the WorkflowPanel and makes it more consistent with the new UI changes introduced in #7443.

Before:

After:

Test me

• Run the difference workflow from main and this branch for the item in the workbench.
  

• Make sure that the functionality and outputs remain unchanged

• Make sure there are no errors

Checklist

• There are unit tests to verify my changes are correct or unit tests aren't applicable (if so, write quick reason why unit tests don't exist)
• I've updated relevant documentation in doc/.
• I've updated CHANGES.md with what I changed.
• I've provided instructions in the PR description on how to test this PR.

[ljowen]

Looks great, that was quick!

Would be good to get @AmberStandley83 's thoughts on wording here, maybe "Back" could be "Edit" or "Close" could be "Save" or "Ok", right now it's not clear which one is taking me to the workbench vs the first panel.

Down the track if we're going to have multistep workflows a "wizard" style UI could be used here but thats for a later date