[CMAKE] Prepare the application bundle for localization

Summary:
This diff adds the files required to setup localization for the
application bundle (lproj). There is no associated translation at the
moment, they will be added in a later diff.

Test Plan:

ninja BitcoinABC-Qt

The generated .app should run on OSX.

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D4379