[Notebook] hide trashcan during edit; add shortcut keys

[johnriedel]

Closes #7651

Describe your changes:

1. hide trashcan when notebook entry is in edit mode
2. implement "Escape" shortcut key to cancel creation/editing of entry
3. implement "Control+Enter" shortcut key to commit notebook entry

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Is this a notable change that will require a special callout in the release notes? For example, will this break compatibility with existing APIs or projects that consume these plugins?

Author Checklist

• Changes address original issue?
• Tests included and/or updated with changes?
• Has this been smoke tested?
• Have you associated this PR with a type: label? Note: this is not necessarily the same as the original issue.
• Have you associated a milestone with this PR? Note: leave blank if unsure.
• Testing instructions included in associated issue OR is this a dependency/testcase change?

Reviewer Checklist

• Changes appear to address issue?
• Reviewer has tested changes by following the provided instructions?
• Changes appear not to be breaking changes?
• Appropriate automated tests included?
• Code style and in-line documentation are appropriate?

Testing Instructions

1. Add a notebook to your OpenMCT items in the left navbar.
2. Click the "+" prompt to start a new notebook entry.
3. Note the textarea is visible, but there's no trashcan icon in the upper right corner of the entry.
4. Enter text into the text area and press CTRL+ENTER.
5. Note the entry successfully saves.
6. Note the trashcan icon is visible in the upper right corner of the entry when you mouse-over the entry.
7. Add a second notebook entry, but instead of saving it, navigate away from the notebook page by clicking "My Items" in the left navbar.
8. Navigate back to the notebook and notice your entry had been successfully saved.

[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 57.26%. Comparing base (1fde0d9) to head (45f8b50).

Files with missing lines	Patch %	Lines
src/plugins/notebook/components/NotebookEntry.vue	20.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7991      +/-   ##
==========================================
- Coverage   57.59%   57.26%   -0.33%     
==========================================
  Files         678      678              
  Lines       27426    27430       +4     
  Branches     2692     2692              
==========================================
- Hits        15795    15709      -86     
- Misses      11288    11378      +90     
  Partials      343      343              

Flag	Coverage Δ
e2e-ci	62.84% <ø> (+0.02%)	⬆️
e2e-full	23.65% <ø> (-18.35%)	⬇️
unit	49.32% <20.00%> (-0.05%)	⬇️

Files with missing lines	Coverage Δ
src/plugins/notebook/components/NotebookEntry.vue	15.60% <20.00%> (+0.18%)	⬆️

... and 8 files with indirect coverage changes

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