feature: add opbnb networks' genesis

[redhdx]

Description

Users can now start nodes on opBNB mainnet or testnet without relying on geth init genesis.json.

Rationale

For builtin networks, running without geth init is convenient.
There are two builtin networks opbnb mainnet and testnet.

Example

You can start opbnb mainnet or testnet without init genesis.json by add command --opBNBMainnet or --opBNBTestnet in the first time to start new node.
If you have already inited genesis.json, you can still use these two command lines, which will check whether the content of your init is correct.
Please ignore opBNBQANet, it is for internal testing only.

Changes

Notable changes:

• Include the opbnb mainnet and testnet genesis block data.
• Add --opBNBMainnet and --opBNBTestnet command lines.
• Add start description log which opbnb network to use.
• Rename opBNBDevnet to opBNBQANet.

[welkin22]

LGTM