Set flash in test session when necessary.

`to_session_value` returns nil when empty.
Fix parsed token value with header `Authorization token=`.
PG arrays should type cast user input

We guarantee that `model.value` does not change after
`model.save && model.reload`. This requires type casting user input for
non-string types.
Merge pull request #15686 from sgrif/sg-pg-int-arrays

PG arrays should type cast user input
Merge pull request #15683 from larrylv/fix-token-with-empty-value

Fix parsed token value with header `Authorization token=`.
Merge pull request #15682 from tgxworld/controller_test_process

Set flash in test session when necessary.