Fix tag bug

[marthacryan]

Fixes #2751. Cleans up metadata editor tag code to fix tag saving bug.

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[kiersten-stokes]

Functionality looks good to me!

[karlaspuldaro]

Looks good, tags changes are now being saved as expected, thanks @marthacryan !
I just found a new bug in validating tags - adding empty space(s) tag through the UI cannot be removed and the metadata cannot be saved either.
Let me know if I should open a new issue for this.

[marthacryan]

Thanks @kiersten-stokes and @karlaspuldaro for testing it out! @karlaspuldaro I added a fix for the empty spaces bug you found cause it was a quick fix.

[karlaspuldaro]

LGTM. Thx for also addressing the empty tag bug here!