New attribute textFontWeight for selecting weight in the font family

Note that AppCompatTextView doesn't work well with this attribute since
it overwrites the selected Typeface.

Bug: 63135308
Test: atest android.widget.cts.TextViewFontWeightTest
Change-Id: I76ee5e3007ea5f96249d2a0bfb66ff5975c62522
5 files changed