Add crc helpers for writing to large buffers.

[DmitriyMusatkin]

Issue #, if available:

Description of changes:
we defined all crc functions to take int for length and then in every binding we have code to work around buffers that are more than INT_MAX.
This just add same helper here so we can skip repeating it in every binding.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[graebm]

Suggested change

	T aws_large_buffer_apply_##Name( \
	static T aws_large_buffer_apply_##Name( \

[graebm]

Or don't declare a separate function here, just have it be the implementation like:

#define CHECKSUM_WITH_SIZE_IMPL(Name, T) \
   ...                                   \
   return val

and then

uint32_t aws_checksums_crc32_with_size(const uint8_t *input, size_t length, uint32_t previous_crc32) {
    CHECKSUM_WITH_SIZE_IMPL(aws_checksums_crc32, uint32_t);
}

[DmitriyMusatkin]

i prefer to keep a separate function here, mostly to sanity check that function pointer prototype has args that match the other args passed to this function.