Consolidate static/dynamic symbol table logic with `elf-edit`

[RyanGlScott]

Data.Macaw.Memory.ElfLoader has two very intricate functions for computing the static symbol table:

https://github.com/GaloisInc/macaw/blob/e4b198ab2dd882e34690ed33056d5231b2d776bf/base/src/Data/Macaw/Memory/ElfLoader.hs#L1330-L1347

And the dynamic symbol table:

https://github.com/GaloisInc/macaw/blob/e4b198ab2dd882e34690ed33056d5231b2d776bf/base/src/Data/Macaw/Memory/ElfLoader.hs#L1636-L1646

It turns out, however, that elfStaticSymbolTable is essentially identical to decodeHeaderSymtab from elf-edit. We should remove macaw's code in favor of decodeHeaderSymtab. Moreover, the dynamic symbol table logic in macaw really ought to belong in elf-edit as well, so that code should be migrated over to elf-edit for others' benefit.

[RyanGlScott]

A handful of thoughts that I wanted to record while looking into this:

• One peculiar aspect of dynamicEntries is that it will only compute function symbols if the header type is ET_DYN, i.e., if we are dealing with a shared object. I'm honestly not sure why this check is here, since it means that dynamicEntries will always be empty for non–position-independent executables, even if they otherwise contain dynamic function symbols.

  I propose that when we move this code to elf-edit, we omit the ET_DYN check. We might even consider removing it from macaw itself, as I'm unclear on what purpose it serves, although this is not strictly required.

• There is another way to compute the dynamic symbol table by using elf-edit's dynamicEntries and dynSymEntry functions. (See this part of the elf-edit test suite for an example of how to do this.) In fact, this way of computing the dynamic symbol table gives you strictly more information that how macaw computes it, as elf-edit's way also gives you symbol version information.

  That being said, I still think that it would be worth putting the code from macaw code into elf-edit, as it provides a much more straightforward API. You won't get symbol versions with this API, but that's arguably a more niche requirement.