Added PE utils for sections and directories

[daladim]

Hello,

Here are a few utility functions that I'm currently using in my own projects, but that I think everyone could benefit from, so this could make sense to upstream them :-)

[philipc]

Thanks for the PR! I've reimplemented ImageDataDirectory::file_offset_range in #421 for better consistency with the existing APIs. Did you still need Section::contains_rva and SectionTable::section_at or were they only to support ImageDataDirectory::file_offset_range?

[daladim]

Thanks for this other PR, that's indeed probably more suitable as what I proposed :-)

Regarding Section::contains_rva and SectionTable::section_at, I happen to use SectionTable::section_at in my projects (but not contains_rva, at least not directly).
I'd not be surprised that other people as well could need both of them one day (in case they want to do some kind of manual parsing or displaying of PE files themselves). Thus, I think that would make sense to still provide them in the public API, but that's up to you to decide (and if you want me to, I can add a commit on top your MR to implement them).

[philipc]

They're still fine to add. You can probably update this PR, since I won't merge the other yet. Maybe rename section_at to something pe_section_containing or something like that, and rename contains_rva to pe_contains_rva (since these types are used for both PE and COFF, but these functions only apply to PE).

[daladim]

Sorry for the delay, I was quite busy last week.
Since I saw you've merged #421, I have rebased on 0.28.3, and I have added Section::contains_rva and SectionTable::section_at, which is quite a trivial change now.

[philipc]

Thanks!