Audit branch

[Evan-Kim2028]

• Refactored the env variables and flags to use urfav cli v2 library.
• Refactored repository to reorganize around main.go and everythig else in "internal" package
• removed self creation of hTTP client
• check return body contents in sendBundle function
• replaced context.Background() with context.WithTimeout
• added contract addresses as env variables

[Evan-Kim2028]

• Added unit tests coverage for bidderapi.go functions sendPreconfBid and sendBid. These are the most important functions and will likely change the most over time in future releases
• switched geth logging for zerolog logging
• refactored environment variables for more simplicity, simplifed main.go logic
• refactored sendBid function to be more modular

[Evan-Kim2028]

• used more context timeout modifications
• changed logging from zerolog to standard library logging
• refactor environment variable handling
• updated go mod and version
• refactor minor formatting and reduce logic complexity

[mrekucci]

I would suggest creating a service struct in which you set all the necessary options that are known at the time of creation and will not change (e.g. default timeout, rpcurl, etc.) and fields that must maintain some state (e.g. logger, ethclient, httpclient, etc.). Then attach existing functions to this structure. This will result in fewer parameters in these methods and avoid global state. Your code will also be easier to mock and test.

[mrekucci]

Instead of this, I'd suggest doing the following:

var (
    bidderAddressFlag := &cli.StringFlag{
        Name:    "bidder-address",
        Usage:   "Address of the bidder",
        EnvVars: []string{"BIDDER_ADDRESS"},
        Value:   "mev-commit-bidder:13524",
     },
     // other flags...
)

// Now below you can do:
c.String(bidderAddressFlag.Name)

[mrekucci]

Consider using some sort of prefix (maybe PRECONF_BOT) for all env variables to avoid collisions or so that they already exist.

[mrekucci]

The c.Context should be used as parent context in all places where you create a new context. This will help you shutdown the app gracefully.