Split bettertogether test case into router and session test cases

Created two new directories (session and router) and moved the relevant files into each. Then updated package names to point to the right places.

Bug: 349106078
Test: Run presubmit and validate that all of the tests are still passing in both new test cases.
Flag: EXEMPT refactor
BYPASS_PS_FLAG_CHECK: updating TEST_MAPPING to point to moved tests
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:730eafdd78ba1036645632c8cf190670ac4a49d9)
Merged-In: I660a38fcc557351a13d6d76ce797e88e590b2726
Change-Id: I660a38fcc557351a13d6d76ce797e88e590b2726
1 file changed