Utility function for comparing hashes

[mattyg]

I would like a utility function to compare 2 hashes.

I've been using isEqual from lodash but discovered an edge case yesterday where it doesn't work: after round-tripping a dna hash to base64 and back, it will incorrectly consider 2 equivalent hashes not equal.

It seems like everyone has their own implementation of hash comparison in their own libs or apps. For example:

• https://github.com/holochain/app-store-gui/blob/4a06139c4ba7d91c7404d79e572d272ecb182060/src/common.js#L159
• https://github.com/holochain-apps/kando/blob/c96fca4e67f995e2047710949ec0dd4646964886/ui/src/util.ts#L36

We should make a canonical one and include it in the client lib. Maybe after some profiling to find the most efficient implementation.

[mattyg]

isEqual still works -- the issue was caused by #265