convert build flags to textproto, initial pass RESTRICT AUTOMERGE

Bug: 328495189
Test: manual
Ignore-AOSP-First: manually adjusting multiple branches
Merged-In: I2f7269431ea16360b8d5fec6b16040a8602e893e
Merged-In: I7d40e5bb923cf84609e2f3a3cbd47c5a5d03a983
Change-Id: I2f7269431ea16360b8d5fec6b16040a8602e893e