refactor(xrp): use ripple-lib connection for API requests

[faustbrian]

Resolves #92

Currently running into an issue with mocking the WebSocket requests that ripple-lib sends, will need to figure out how to intercept them with nock.

Update 1
Doesn't seem to be possible to mock websocket with nock nock/nock#129 so might need to mock the whole module via jest.

Update 2
Ripple runs a local server that replies with stub data https://github.com/ripple/ripple-lib/blob/f1c1c7033a554823b489fd3c53d27ee12fc76ed1/test/setup-api.ts#L6-L22 so will probably have to do the same.

[codecov]

Codecov Report

Merging #93 into master will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #93      +/-   ##
==========================================
+ Coverage   80.17%   80.29%   +0.11%     
==========================================
  Files          23       22       -1     
  Lines         686      619      -67     
  Branches      108      103       -5     
==========================================
- Hits          550      497      -53     
+ Misses        133      118      -15     
- Partials        3        4       +1     

Impacted Files	Coverage Δ
src/dto/delegate.ts	33.33% <0.00%> (-16.67%)	⬇️
src/services/client.ts	67.00% <0.00%> (-4.43%)	⬇️
src/transformers/market-transformer.ts	92.85% <0.00%> (-1.59%)	⬇️
src/services/message.ts	87.50% <0.00%> (-0.74%)	⬇️
src/transformers/historical-price-transformer.ts	100.00% <0.00%> (ø)
src/transformers/historical-volume-transformer.ts
src/services/identity.ts	81.39% <0.00%> (+0.93%)	⬆️
src/services/transaction.ts	60.00% <0.00%> (+2.30%)	⬆️
src/services/tracker.ts	93.02% <0.00%> (+10.16%)	⬆️

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