Add initial javascript library

[rrrliu]

Adds signal generation functions to JS to be used in burner wallet, metamask core and other wallet extensions.

Uses yarn pnp, but the amcl-js library was incompatible with installing, so files were copied over the and put into the amcl-js directory.

Remaining follow-ups for future changes:

• more rigorous test cases (add verification like we have in rust)
• remove unnecessary amcl-js files
• npm package registry
• linking with burner wallet
• erc spec + metamask core

[lsankar4033]

could publish a mirror of amcl-js at (i.e.) personaelabs/amcl-js to unbundle it from this repo. @Divide-By-0 lmk what you think

[lsankar4033]

otherwise this lgtm!

[rrrliu]

could publish a mirror of amcl-js at (i.e.) personaelabs/amcl-js to unbundle it from this repo. @Divide-By-0 lmk what you think

Updated! Uses a published mirror package now at amcl-js

[lsankar4033]

excellent!