Implements sha3Raw and soliditySha3Raw

[nivida]

Description

Fixes #1961

This PR does fix the referenced "bug" above where you get returned null instead of the hash.

@cgewecke I'm open for better function names ;)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run test with success and extended the tests if necessary.
• I ran npm run build and tested the resulting file from dist folder in a browser.
• I have tested my code on the live network.

[coveralls]

Coverage increased (+0.08%) to 84.426% when pulling d9563da on issue/1961 into 0109937 on 1.x.

[cgewecke]

This LGTM! Really nice.

Only thing I can think of that might be useful to add to the tests is maybe one non-empty-string test case borrowed from the other sha tests, just so the basic functionality is covered in case someone accidentally changes logic later.