[DevUI] Rename Devtools DFM to DevUI DFM; fix build errors.

The name "devtools" already means something specific in Chrome. To
avoid confusion, this CL renames the upcoming DFM for chrome://
internal pages to "Developer UI module", or dev_ui / DevUi for short,
and essentially redoes the CL:
https://chromium-review.googlesource.com/1613558

Other changes:
* To fix build errors, update dev_ui_module_tmpl.gni to adapt to recent
  changes re. manifest package, from
  https://chromium-review.googlesource.com//1667687
* Rename DevtoolsUI.java to DevUiModuleProvider.java, which will play
  a greater role for DFM installation than initially thought.
* Change GN enablement flag to |dfmify_dev_ui| (was |dfmify_devtools|).

Bug: 927131
Change-Id: I500451658e7fd575e6b499e9eafbb221d0e30ad6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1681872
Reviewed-by: Robert Kaplow (slow) <rkaplow@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#674489}
10 files changed