Have more meaningful error message

When building a PreapprovalDetails oblject, throwing IllegalArgument-
Exception with a message explaining what was missing instead of a
NullPointerException without any message. Due to the limitation,
manually construct the Builder and related methods instead of using
codegen.

Fix: 269731101
Test: atest CtsContentTestCases:PreapprovalDetailsTest
Test: atest CtsPackageInstallTestCases:PreapprovalInstallTest
Test: manually building a PreapprovalDetails object with supplying
      all required details, and check if the message tells me what
      is going on.
Change-Id: I0cd641d90ab45830ab6740e94357e4280fac2d4c