refactor: rename passphrase to mnemonic

[faustbrian]

Resolves #340

[codecov]

Codecov Report

Merging #344 into master will decrease coverage by 4.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #344      +/-   ##
==========================================
- Coverage   85.69%   81.61%   -4.09%     
==========================================
  Files          28       28              
  Lines         860      718     -142     
  Branches       94       57      -37     
==========================================
- Hits          737      586     -151     
- Misses        122      130       +8     
- Partials        1        2       +1     

Impacted Files	Coverage Δ
src/services/peer.ts	0.00% <0.00%> (-87.50%)	⬇️
src/services/transaction.ts	40.74% <0.00%> (-20.34%)	⬇️
src/services/fee.ts	78.57% <0.00%> (-17.86%)	⬇️
src/services/client.ts	80.13% <0.00%> (-8.35%)	⬇️
src/services/message.ts	90.47% <0.00%> (-5.18%)	⬇️
src/services/identity/keys.ts	84.00% <0.00%> (-4.00%)	⬇️
src/services/ledger.ts	91.66% <0.00%> (-0.34%)	⬇️
src/services/identity/wif.ts	100.00% <0.00%> (ø)
src/dto/transaction.ts	94.73% <0.00%> (+3.43%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5b45733...cfdf526. Read the comment docs.