ImageGenerator: add an option to specify the supported locales

A smaller list of locales helps to reduce the size of the generated
images; and mitigate the additional space requirement on the tight boot
image for some devices. The caller of the program will be responsible
for providing the locale list.

Also add a verbose option and switch to logger.

Bug: 74397117
Test: generate and check the image
Change-Id: I7b7cee681ccdc6e13fdd0575cf02f8add2ad9a2d