### Description
This pull request removes duplicated code related to MongoDB connection/disconnection attempts. This code was copied across all 8 microservices.
The functionality is now unified under the `common/dbutil` package.
### Description
This pull request implements an improvement in the processing logic of the `tx-tracker` service to avoid processing a message more than once.
### Summary
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/415
When the `tx-tracker` service processes a VAA, sometimes the transaction is not finalized (e.g.:for chains with slow finality, VAAs with low consistency level, out-of-sync nodes). This problem was observed on chains like Solana, Ethereum and Polygon, but could have happened on other chains.
This pull request adds the logic needed to wait and retry processing the VAA, hoping that the originating transaction reaches finality.
Also, the `tx-tracker` service now uses a worker pool to process transactions, which will lead to higher throughput. This will benefit the WormholeScan UI, specially in the case when a large number of VAAs are emitted in a short period of time.
### Summary
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/404
The WormholeScan UI needs to display the sender address for each token bridge VAA. This pull request modifies the `tx-tracker` service to obtain that information for Solana and eight EVM chains.
The transaction sender will become accessible through the following endpoints:
* `GET /api/v1/global-tx/{chain}/{emitter}/{seq}`: field `originTx.from`.
* `GET /api/v1/transactions`: field `originAddress`.
In both cases, the field is nullable (i.e.: sometimes it may not be available due to eventual consistency or internal errors)
### Summary
This pull request adds the functionality to search for VAAs using Solana tx hashes, e.g.:
`GET /api/v1/vaas?txHash=2qnNNBQQQ152sGkQ1Rnq2Kdr48LvdN4oXwnTWyEmJqYYWFusLWxbwhpGS5KTXH1bKKx9gg9BLZMKd3g1cXiy7QMz`.
Also, the VAA objects returned by the API now have a new field `nativeTxHash`, which contains the tx hash that generated the VAA in the native format of the emitter chain.
Tracking issues: https://github.com/wormhole-foundation/wormhole-explorer/issues/212, https://github.com/wormhole-foundation/wormhole-explorer/issues/214
### Testing guidelines
Endpoints affected:
* `GET /api/v1/vaas` now supports Solana tx hashes by using the `?txHash=` query parameter. This search is limited to VAAs created by the portal token bridge.
* Some VAAs returned by the API should have a new field `nativeTxHash`. All VAAs related to the portal token bridge should have this field set.
* An internal refactoring affected pretty much all routes under `GET /api/v1/vaas*`, which should be re-tested.
* In the response of `/api/v1/global-tx/`, the field `originTx.signer` has been renamed to `originTx.from`
### Summary
The tx-tracker service was exceeding node RPC rate limits, which caused it to fail.
This pull request changes the APIs upon which the service depends to avoid the same issue in the future.
Also, the backfiller job has been updated accordingly.
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/205
Agustin Pazos
ftocal
agodnic