### Description
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/377
This pull request modifies the analytics service so that it persists price information for a VAA in MongoDB. Data is stored only for token bridge VAAs, and only if the price is cached for the symbol being used.
A new collection `transferPrices` has been created, with the following document model:
```
{
"_id": "22/0000000000000000000000000000000000000000000000000000000000000001/18087",
"price": "0.999684",
"symbol": "USDC",
"timestamp": 2023-06-06T14:04:47.000+00:00
"tokenAmount": "0.1",
"usdAmount": "0.0999684"
}
```
Fernando Torres
walker-16
ftocal
gipsh
agodnic