### 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
Tracking issue: https://github.com/wormhole-foundation/wormhole-explorer/issues/254
For all chains except Solana, the data in `globalTransactions.sourceTx` was somewhat duplicated, since we already had that data in the `vaas` collection.
This pull request changes the `tx-tracker` service so that no redundant data will be written, and also changes the API to look up the data from the `vaas` collection instead.
The responses from the endpoint `/api/v1/global-tx` will no longer contain the field `originTx.from`.
agodnic