[llvm-readobj] - Change how we create DynRegionInfo objects. NFCI.

Currently we have `checkDRI` and two `createDRIFrom` methods which
are used to create `DynRegionInfo` objects.

And we have an issue: constructions like:
`ObjF->getELFFile()->base() + P->p_offset`
that are used in `createDRIFrom` functions might overflow.

I had to revert `D85519` which triggered such UBSan failure.

This NFC, simplifies and generalizes how we create `DynRegionInfo` objects.
It will allow us to introduce more/better validation checks in a single place.
It also will allow to change `createDRI` to return `Expected<>` so
that we will be able to stop using the `reportError`, which
is used inside currently, and have a warning instead.

Differential revision: https://reviews.llvm.org/D86297