[snap/backend]: Added fee multipler

[AnthonyLaw]

What was the issue?

• The fee multiplier is missing; we will use it to calculate the transaction fee.

What's the fix?

• Added fee multiplier endpoint
• Extract slow, average, and fast multiplier
• Added fetch multiplier in onCronjob

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.38%. Comparing base (23ce5df) to head (d63d9cd).

Additional details and impacted files

[](https://app.codecov.io/gh/symbol/product/pull/1028?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol) ```diff @@ Coverage Diff @@ ## snap/frontend-transaction #1028 +/- ## ============================================================= - Coverage 99.38% 99.38% -0.01% ============================================================= Files 40 12 -28 Lines 1948 324 -1624 Branches 246 57 -189 ============================================================= - Hits 1936 322 -1614 + Misses 12 2 -10 ``` | [Flag](https://app.codecov.io/gh/symbol/product/pull/1028/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol) | Coverage Δ | | |---|---|---| | [snap-backend](https://app.codecov.io/gh/symbol/product/pull/1028/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol) | `99.38% <100.00%> (+0.03%)` | :arrow_up: | | [snap-frontend](https://app.codecov.io/gh/symbol/product/pull/1028/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol) | `?` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/symbol/product/pull/1028?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol) | Coverage Δ | | |---|---|---| | [snap/backend/src/index.js](https://app.codecov.io/gh/symbol/product/pull/1028?src=pr&el=tree&filepath=snap%2Fbackend%2Fsrc%2Findex.js&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol#diff-c25hcC9iYWNrZW5kL3NyYy9pbmRleC5qcw==) | `100.00% <100.00%> (ø)` | | | [snap/backend/src/services/symbolClient.js](https://app.codecov.io/gh/symbol/product/pull/1028?src=pr&el=tree&filepath=snap%2Fbackend%2Fsrc%2Fservices%2FsymbolClient.js&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol#diff-c25hcC9iYWNrZW5kL3NyYy9zZXJ2aWNlcy9zeW1ib2xDbGllbnQuanM=) | `100.00% <100.00%> (ø)` | | | [snap/backend/src/utils/transactionUtils.js](https://app.codecov.io/gh/symbol/product/pull/1028?src=pr&el=tree&filepath=snap%2Fbackend%2Fsrc%2Futils%2FtransactionUtils.js&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol#diff-c25hcC9iYWNrZW5kL3NyYy91dGlscy90cmFuc2FjdGlvblV0aWxzLmpz) | `100.00% <100.00%> (ø)` | | ... and [28 files with indirect coverage changes](https://app.codecov.io/gh/symbol/product/pull/1028/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=symbol)