Fixes #11145

This PR

• Starts uCrop from the preview fragment with the high res image file path.
• Returns to the original post on the Gutenberg editor skipping preview fragment on back action.

P.S.
Few observations related to uCrop fragment which may require separate tasks (adding them as a checklist):

• On back action from the app bar on the uCrop fragment, we want to go to the original post on the Gutenberg editor skipping preview fragment.
  Using popUpToInclusive property for this purpose doesn't pop the start destination (preview fragment) off the back stack in a module.
  On doing so, activity finishes and then a failed attempt is made to reopen the start destination. As a workaround, explicitly invoking back action for the uCrop fragment. Will further investigate it when we pass edited image to the Gutenberg editor.

  Related Android issue here.

  UPDATE: As discussed in comments, workaround looks ok.

• Using temporary options (aspect ratios, crop frame/ grid) and styling as shown in this screenshot. Will update with actual options after a discussion with the designer.
  cc @mbshakti

  UPDATE: Will take care of it in this issue: Update crop screen design #11387.

• The cropping rectangle in the uCrop fragment is currently shown behind the toolbar. As a result we cannot drag upper corners. Propagating events to the view behind (by setting clickable, focusable to false) doesn't seem to be working in case of Toolbar as it eats all touch events, regardless of the clickable attribute and @null background.

@Override
public boolean onTouchEvent(MotionEvent ev) {
  // Toolbars always eat touch events

Will take care of this issue in a separate PR.
UPDATE: Will take care of it in this issue: #11387.

• uCrop doesn't seem to be saving image state and restoring it on orientation change (at least with the version we're using2.2.2). Will investigate it more in a separate task.

  Related uCrop issue here.

  UPDATE: As discussed in comments, leaving this issue to the end of the project. Added a note in the Media Editing project.

• Yet to decide output file path.

  UPDATE: As discussed in comments, output file location is ok.

• Noticed a bug, low res(LR) image was saved to file and sent to uCrop on moving the app to background while LR image was loading and bringing the app to foreground after it was loaded but before HR image was loaded.

  It is probably happening because viewModel.onLoadIntoImageViewSuccess(url) is called again due to the LiveData fact:

  If a lifecycle becomes inactive, it receives the latest data upon becoming active again. For example, an activity that was in the background receives the latest data right after it returns to the foreground.

  Will create an issue and fix it in a separate PR.

  UPDATE: Will take care of it in this issue: Low res(LR) image is saved to file on moving the app to background and bringing it back to foreground when images are loading #11377.

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.