Revert "[Sharesheet] Refactor Sharesheet to map actions by const, not UI string"

This reverts commit 434c4df1.

Reason for revert: Consistent failures of SharesheetBubbleviewBrowserTest.* starting with:

https://ci.chromium.org/ui/p/chromium/builders/ci/Linux%20ChromiumOS%20MSan%20Tests/42192/overview

Original change's description:
> [Sharesheet] Refactor Sharesheet to map actions by const, not UI string
>
> Refactors the Sharesheet Cache and related classes to use const enum
> ShareTypes to distinguish Sharesheet actions, rather than the user
> visible strings.
>
> Clipboard & Quick Share from Files, and Copy to Clipboard, Quick Share,
> and send to Files from Photos App (Arc++).
>
> Bug: b:326633226
> Test: Unit tests, tested that I could manually perform Copy to
> Change-Id: If0ddb1410322aad1d8f4439f775ebe1c1b1166b4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5321767


> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Commit-Queue: Daniel Classon <dclasson@google.com>
> Cr-Commit-Position: refs/heads/main@{#1280233}

Bug: b:326633226
Change-Id: I48c85759f3cdf187a76804c4789c146fc036d471
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5408312


Reviewed-by: Daniel Classon <dclasson@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Stefan Zager <szager@google.com>
Auto-Submit: Stefan Zager <szager@google.com>
Owners-Override: Stefan Zager <szager@google.com>
Cr-Commit-Position: refs/heads/main@{#1280368}