add ALLOW_LOCAL_TIDY_TRUE and some tests

* A new ALLOW_LOCAL_TIDY_TRUE variable, default is false.
* If it is 0/false, local "tidy:true" is ignored.
* If it is 1/true, local "tidy:true" is honored as it is now.

Bug: 229779921
Test: make with and without ALLOW_LOCAL_TIDY_TRUE=1
Change-Id: I0323289a4d3bb2514982252a5a1339e94f2bbaab