[llvm] [NFC] Remove UnwindTable dependency on CIE, and FDE (PR #142520)

[Igor Kudrin via llvm-commits]

igorkudrin wrote:

> I believe `UnwindTable` should be mutable, if not it can be a bunch of functions to operate on a `vector<Row>`. For now it's only updated once during creation, but my use case described in this [RFC](https://discourse.llvm.org/t/rfc-dwarf-cfi-validation/86936) is to update them regularly.

I probably don't see that far, and my review is solely for this (and #142521) change. For now, `UnwindTable` doesn't need to be changed after creation, so I'd prefer it not to have public methods for this. This would clearly distinguish between the two phases of its lifecycle.

> I can move in the direction of making `UnwindTable` a fully pure container of a sequence of rows and make `parseRows` static method or a standalone function.

A standalone function, yes, that is what I meant. Can we give it a shot?

https://github.com/llvm/llvm-project/pull/142520