AutoSize TextView (part 7) - APIs for configuring auto-size

Contains:
* getters/setters for all auto-size config attributes
* verbose JavaDocs
* isolated and reused the setup part of auto-size
* some variables had to become instance fields
* clarified some variable names

In a few words, whenever a configuration setter is
called, the value is assigned and setupAutoSizeTextXY()
gets called. The latter tries to build all the
intermediary values that it needs, attaches default
values, etc. If it is successful then it makes a call
to autoSizeText(), else it throws a runtime exception
with an appropriate message.

Bug: 32221168
Test: attached in the same topic
Change-Id: I448454ef4490102c8cc2b19e0e16e998aeb45cd0