Summary:
Fixes T4066.
add `isActionDisabled()` to DifferentialLandingStrategy, which also explains why it is so.
Make an appropriate pop-up in the controller.
Also make the whole UI "workflow", and convert `createMenuItems()` to `createMenuItem()` (Singular).
Test Plan: Click "Land to..." button in all kinds of revisions.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran
Maniphest Tasks: T4066
Differential Revision: https://secure.phabricator.com/D8105
Summary: I've kept this as close as possible to the Git version for ease of review and later refactoring of them both together. At minimum, the functions to get the working dir should probably be cleaned up one day.
Test Plan: Landed a revision.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran
Differential Revision: https://secure.phabricator.com/D7534
