fix: clean up invalid breadcrumb usages

[bradenmacdonald]

Description

When trying to pull in the newest version of Paragon, some type errors were showing up. I'm fixing some of them in openedx/paragon#4077 but others should be fixed in this repo.

The Paragon Breadcrumb label is used as a key in various places and so should be a string. It also needs to be unique, which seems bad but that's how it's implemented. So I've changed the container changes preview "Back" breadcrumb to a horizontal stack with a button and a title:

Before	After

I also fixed some missing i18n for the word "Back", and changed a user-visible message to not include the term "Breadcrumb" which is a technical term that users may not know.

I also changed target to currentTarget in an event handler. For an element with no children, these will always be the same, but with the changes in openedx/paragon#4077 , only currentTarget will have the correct HTMLElement typing required to access data- attributes, because in theory the target value could be a totally different child element.

Supporting information

Together with openedx/paragon#4077 , this will unblock #2765 .

Testing instructions

Check that the "Library Updates" page is working as normal.

Best Practices Checklist

We're trying to move away from some deprecated patterns in this codebase. Please
check if your PR meets these recommendations before asking for a review:

• Any new files are using TypeScript (.ts, .tsx).
• Avoid propTypes and defaultProps in any new or modified code.
• Tests should use the helpers in src/testUtils.tsx (specifically initializeMocks)
• Do not add new fields to the Redux state/store. Use React Context to share state among multiple components.
• Use React Query to load data from REST APIs. See any apiHooks.ts in this repo for examples.
• All new i18n messages in messages.ts files have a description for translators to use.
• Avoid using ../ in import paths. To import from parent folders, use @src, e.g. import { initializeMocks } from '@src/testUtils'; instead of from '../../../../testUtils'

Private ref: MNG-4846

[openedx-webhooks]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.07%. Comparing base (0b2b8e1) to head (40bedd1).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2811   +/-   ##
=======================================
  Coverage   95.07%   95.07%           
=======================================
  Files        1267     1267           
  Lines       29292    29292           
  Branches     6692     6692           
=======================================
  Hits        27850    27850           
  Misses       1372     1372           
  Partials       70       70           

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[ChrisChV]

@bradenmacdonald The code looks good! But, in my instance, the change is noticeable:

[navinkarkera]

@bradenmacdonald Yes, it looks a bit weird. The unicode arrow looks small.

[bradenmacdonald]

@ChrisChV @navinkarkera Weird, I wonder why it's so different for you guys. I thought with web fonts these days, things would be more consistent than that. How about I just change it to not use Breadcrumb at all then? Just having a "back" button may not really be a proper usage of breadcrumb anyways (?) A horizontal stack will work just as well.

[navinkarkera]

@bradenmacdonald That should work.

[bradenmacdonald]

@ChrisChV @navinkarkera I've updated this PR. Can you please take another look?

[navinkarkera]

@bradenmacdonald Looks good.

[navinkarkera]

Suggested change

	<Button variant="link" className="px-0" onClick={onBackBtnClick}>
	<Button variant="link" className="px-0 text-gray-900" onClick={onBackBtnClick}>