Update language to comply with Android's inclusive language guidance
See https://source.android.com/setup/contribute/respectful-code
for reference
Bug: 162364131
Bug: 162536543
Test: aapt2_tests
Change-Id: I4eef925d6319b40a395fc8d59a3f2912a02ca03b
A resource defined like so:
<item type="drawable" name="foo" />
should be assigned the value @null.
The only exception is for <string> resources, which are given the
empty string value (since <string></string> is ambiguous). The decision
to use "" is based off the fact that old AAPT used to assign "" to all
undefined resources, even non-string ones.
Bug: 38425050
Test: make aapt2_tests
Change-Id: Ib3e0f6f83d16ddd8b279c9fd44a07a37867b85e9
