Add endian keyword argument to type reads

[Schamper]

Partially solves #143, but I'd still like the context manager approach to be in there too. But that depends on #140.

Adds the ability to override the endianness on single type reads. So for example:

In [1]: from dissect.cstruct import cstruct

In [2]: cs = cstruct(endian="<")

In [3]: hex(cs.uint32(b"\x01\x02\x03\x04"))
Out[3]: '0x4030201'

In [4]: hex(cs.uint32(b"\x01\x02\x03\x04", endian=">"))
Out[4]: '0x1020304'

This should work on any type, including structs, unions and pointers.

Because the function signature for type reading and writing changes because of this, I also added a check when adding a custom type to ensure it's signature is correct. If it's not, it will either throw a (descriptive) error or issue a warning. I also intentionally added a **kwargs to the function signature to allow for future expansion without breaking backwards compatibility again.

I'm not 100% if the behavior of pointers is as expected. I implemented it so that:

• If you don't override endianness, it'll take it from the cstruct instance (like everything else)
• If you override endianness, it'll be used for both the parsing of the pointer value and the dereferencing
• You can additionally override on .dereference(endian=)
• As with everything else, calling .dumps() will fall back to the cstruct instance endianness, unless overridden

[codecov]

Codecov Report

❌ Patch coverage is 96.13527% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.83%. Comparing base (194b1b5) to head (8a6b8b6).

Files with missing lines	Patch %	Lines
dissect/cstruct/types/base.py	92.30%	3 Missing ⚠️
dissect/cstruct/cstruct.py	89.47%	2 Missing ⚠️
dissect/cstruct/utils.py	88.23%	2 Missing ⚠️
dissect/cstruct/types/pointer.py	97.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #144      +/-   ##
==========================================
- Coverage   93.01%   92.83%   -0.18%     
==========================================
  Files          21       21              
  Lines        2435     2472      +37     
==========================================
+ Hits         2265     2295      +30     
- Misses        170      177       +7     

Flag	Coverage Δ
unittests	92.83% <96.13%> (-0.18%)	⬇️

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