Do not throw exception when there is no omapi reader supported

Add cts tests to make sure the result of getReaders() aligns omapi feature
flags. Do not throw exception when there is no omapi readers.

Bug: 131062577
Test: atest CtsOmapiTestCases
Change-Id: I2ad0057adb975ffcbf9bd5d6a9788bc79bd860e3
1 file changed