## Description
Previously, the notional cache was using the `float64` type to manipulate price data. Since floating point types can't represent price data accurately, this commit changes the codebase to use a lossless representation (i.e.: `decimal.Decimal`).
### Summary
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/344
Before this pull request, there were two separate token databases (one being used by the InfluxDB backfiller, and another one in the `common/` module being used by the analytics service).
Having two different token databases resulted in inconsistencies, due to each of these databases containing different tokens.
This PR unifies those two databases into a single one, under the `common/` module.
### Summary
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/275
This pull request implements the endpoint `GET /api/v1/top-chain-pairs-by-num-transfers`, which returns the chain pairs that have the most transfers.Internally, the endpoint uses data summarized daily to speed up query execution times.
This endpoint has a mandatory query parameter named timerange, which must be set to `7d`, `15d` or `30d`.
### Summary
In order to compute volume metrics for each token, we need metadata about the token that is not present in the VAAs (e.g.: decimals, symbol).
That information is statically defined in `common/domain/tokenbridge.go`. This pull request adds the most relevant tokens (i.e.: the tokens that contribute the most volume) to the existing definitions. It is very likely that more token definitions will be added in the future as needed.
The token metadata that was previously defined in the `notional` package (symbols, coingecko IDs) was also moved to `common/domain/tokenbridge.go`.
Tracking issue https://github.com/wormhole-foundation/wormhole-explorer/issues/281
### Summary
This pull request adds volume metrics to influxdb. Also, it adds the 24h volume metric to `GET /api/v1/scorecards`.
Tracking issues: https://github.com/wormhole-foundation/wormhole-explorer/issues/221, https://github.com/wormhole-foundation/wormhole-explorer/issues/280
### Changes:
* The `parser` service no longer generates metrics for influxdb. All metrics-related code was removed from that service, that code was moved to the analytics service instead.
* New volume metrics were added to the analytics service.
* The notional cache was modified to use token names (i.e.: ticker symbols) as keys instead of chain IDs.
* The notional cache reader was moved to the `common/client/cache` package.
* A little bit of duplicated code between the cache reader and writer was removed.
* A 24h volume metric was added to `GET /api/v1/scorecards`.
* A dictionary that stores token metadata was added under `common/domain/tokenbridge.go`. More tokens will be added to it in the near future.
agodnic
walker-16
ftocal