Mark RGB++ Info for Signet

[Keith-CY]

This feature request comes from the community

There will be one more BTC testnet, named signet(https://mempool.space/signet) for the RGB++ application because the performance of BTC testnet was impacted.

The following updates are required:

1. verify the transaction on BTC testnet and BTC signet simultaneously when an RGB++ transaction is synced @rabbitz
2. deploy one more BTC live UTXO monitor for the signet @Daryl-L
3. Mark the new cell config in the frontend @Keith-CY

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Ref:

• Support BTC signet network: https://github.com/ckb-cell/typeid-contract-cell-deps/pull/4/files#diff-66c441555523cc5f71a1d1badbb91da5184b9177882553b34fdc593af3931648R17-R20

[Keith-CY]

3. Mark new cell config in the frontend will by updated by nervosnetwork/ckb-explorer-frontend@18f54cb

[Daryl-L]

bitcoin check service has already been deployed for signet, testnet and the mainnet.

[rabbitz]

PR: nervosnetwork/ckb-explorer#1966

[FrederLu]

Testnet verified.