Fix case-sensitive comparisons of Android/media

There are several places where we determine things based on whether a
path contains Android/media - but these need to be compared ignoring
case.

Factored out common methods in StringUtils, fixed package name of
StringUtils.

Bug: 195101715
Bug: 209892068
Test: atest FileUtilsTest
Test: TEST_MAPPING
Change-Id: Iaf381750bba12654159e943cc9dfe8e87f92cbcd
Merged-In: Iaf381750bba12654159e943cc9dfe8e87f92cbcd
12 files changed