Rather than have dismantle-tablegen's tests go looking for .tgen files in other projects, move the parser testing functionality into the library, where it can be called by the tests of those projects which already depend on it.
Simplify parserTest code to only look in local project's data/ directory
Remove redundant AArch64.tgen file in dismantle-tablegen
Also check data/override/*.tgen files
Call parserTest in other dismantle projects' tests
Lightly reorganize some imports while we're in there
Rather than have dismantle-tablegen's tests go looking for .tgen files in other projects, move the parser testing functionality into the library, where it can be called by the tests of those projects which already depend on it.
parserTestcode to only look in local project's data/ directoryparserTestin other dismantle projects' tests