Use consistent naming in ZetaClient

[lumtis]

Describe the Issue Some different tasks that can be addresses in the same PR to make the naming in ZetaClient more consistent

• We use “ob” for many variable name. While this can be evident that this is “observer” for us, this might not be for newcomers.
  • We should use more explicit variable name “observer”
  • ob name is used extensively, example: the BTC or EVm client. The observer should be the overall software orchestrating CCTXs, the component interacting with a specific chain should be named evmClient, bitcoinClient
• We sometime have unnecessary prefixes
  • Example: bitcoin_client, bitcoin_signer in bitcoin package. If the package is already named bitcoin we can simply use client, signer for the name, bitcoin is the namespace
  • Same for evm
• Already tracked but we should use Inbound for InTx and outbound for outTx
• All UTXOS occurence should be renamed to UTXOs
• All Tss occurences should be renamed to TSS
• All broadcasted occurences should be renamed to broadcast
• All occurence of Btc should be BTC, Eth → ETH (ZetaCore might be concerned)
• All CrossChain occurences should be renamed to Crosschain
• All Cctx occurences should be renamed to CCTX
• All InBound occurences should be renamed to Inbound (same for Outbound)
• Remove “manager” naming as it is too generic
  • Example: outTxProcessorManager: OutTxProcessor
  • TSSKeysignManager

Seems like we use sometime "observer" and "watch" terms for the same signification