Add Rainbow Wallet support

[dmytrotkk]

In the latest update Rainbow announced custom networks support, so now it's possible to add it the list of available wallets in the SKALE Metaport / SKALE Portal.

2 issues should be fixed to add Rainbow Wallet:

1. Error when adding a new network from Metaport - it fails with User rejected request(network added successfully)
2. Error when transaction is mined:

Error: invalid value for value.gasPrice (invalid BigNumberish value (argument="value", value={ "hex": "0x0186a0", "type": "BigNumber" }, code=INVALID_ARGUMENT, version=6.7.1)) (value={ "accessList": null, "blockHash": "0x639caf2a7cd5c24503728534475e0142301ac04be9ff031b1e072b383badfd3b", "blockNumber": 7374691, "chainId": 1564830818, "confirmations": 1, "creates": null, "data": "0x850495060000000000000000000000000000000000000000000000000000000000000060000000000000000000000000d162bb5c75fe99144295b03510bab2df9961744000000000000000000000000000000000000000000000000006f05b59d3b20000000000000000000000000000000000000000000000000000000000000000000f656c617465642d74616e2d736b61740000000000000000000000000000000000", "from": "0x83b7b3A59857188474FF0269cCC3859b46479aaF", "gasLimit": { "hex": "0x025be2", "type": "BigNumber" }, "gasPrice": { "hex": "0x0186a0", "type": "BigNumber" }, "hash": "0xee197b29f0fc4f61428ccc0cfe06f06a05df9f3d54452a944bab85553396fd48", "nonce": 5, "r": "0xe475056d4a75714815a44d69420ff4544b2866c9b178c8dfa776cc9130b85a78", "s": "0x4c2d171f6f1be584f4f4304c9b681e22fbc3461e1163fe3e57500b4d4c0c2fd2", "to": "0xD2aAA00500000000000000000000000000000000", "transactionIndex": 5, "type": 0, "v": 3129661672, "value": { "hex": "0x00", "type": "BigNumber" } }, code=BAD_DATA, version=6.7.1)
    at makeError (chunk-2ZIMCCBD.js?v=bd740906:324:15)
    at assert (chunk-2ZIMCCBD.js?v=bd740906:334:11)
    at chunk-2ZIMCCBD.js?v=bd740906:14384:9
    at formatTransactionResponse (chunk-2ZIMCCBD.js?v=bd740906:14521:5)
    at BrowserProvider._wrapTransactionResponse (chunk-2ZIMCCBD.js?v=bd740906:15582:36)
    at BrowserProvider.getTransaction (chunk-2ZIMCCBD.js?v=bd740906:15905:17)
    at async checkTx (chunk-2ZIMCCBD.js?v=bd740906:17071:21)