[llvm-readobj][test] - Improve testing in hash-table.test

This makes tests stricter and adds cases to verify what
we do when:

1) there is no `DT_HASH` tag (but there is a `SHT_HASH` section in sections header)
2) the sh_entsize of the `SHT_HASH` section is not equal to 4.

Differential revision: https://reviews.llvm.org/D88812