CT-364: Convert Wallet and Wallets to ES6 class and improve type support

[tylerlevine]

• Refactor example keycard code into separate file
• Introduce and begin using standard callback type
• Fix inconsistent error behavior in some methods

[codecov]

Codecov Report

Merging #389 into master will increase coverage by 22.1%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #389      +/-   ##
==========================================
+ Coverage   38.41%   60.52%   +22.1%     
==========================================
  Files          70       72       +2     
  Lines        9644     9689      +45     
  Branches     2092     2122      +30     
==========================================
+ Hits         3705     5864    +2159     
+ Misses       5324     2897    -2427     
- Partials      615      928     +313

Flag	Coverage Δ
#integration	38.4% <ø> (-0.02%)	⬇️
#unit	54.35% <ø> (?)

Impacted Files	Coverage Δ
src/v2/keycard.ts	2.75% <0%> (ø)
src/v2/trading/trade.ts	100% <0%> (ø)
src/v2/coins/bsv.ts	35.06% <0%> (+1.29%)	⬆️
src/keychains.ts	34% <0%> (+1.33%)	⬆️
src/util.ts	64.78% <0%> (+1.4%)	⬆️
src/v2/coinFactory.ts	94.62% <0%> (+2.15%)	⬆️
src/v2/coins/token.ts	71.52% <0%> (+2.64%)	⬆️
src/v2/coins/tbch.ts	78.57% <0%> (+3.57%)	⬆️
src/v2/coins/txlm.ts	78.57% <0%> (+3.57%)	⬆️
src/index.ts	96% <0%> (+4%)	⬆️
... and 43 more

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[dannydeezy]

Is this an entirely new file, or was it copied from somewhere else?

[tylerlevine]

It's a new file, but the code was extracted out of wallet.ts

[dannydeezy]

reviewed in person with tyler, looks good!