Fix and expand tests for get/setSystemSelectionChannels

1. Call getSystemSelectionChannels to get the current list of bands for
   resetting the test.
2. Call setSystemSelectionChannels in a loop for every possible band. If
   it succeeds (modem supports the band), add the band to the list of
   modem-supported bands and verify that getSystemSelectionChannels
   returns the band that was set.
3. Call setSystemSelectionChannels with a list of empty bands and verify
   no error.
4. Call setSystemSelectionChannels with the list of all modem-supported
   bands created in #2 and verify no error.
5. Call getSystemSelectionChannels to get the list of all
   modem-supported bands and verify that this list matches the one
   created in #2.
6. If getSystemSelectionChannels exists, call
   setSystemSelectionChannels with the initial list of bands from #1
   to reset the test.

Test: atest CtsTelephonyTestCases:TelephonyManagerTest
Bug: 255821693
Change-Id: I752ab4a7afe240c7beb652e1d0455cfe6fc7e587
(cherry picked from commit 83098d063f4e368ad9b7168f36653daa4566cbd7)
Merged-In: I752ab4a7afe240c7beb652e1d0455cfe6fc7e587