feat: add Erc20 contracts

[0xverin]

Context

resolves p-845
resolves p-846
This PR mainly implements the ERC20 contract on BSC and Ethereum networks.

Labels

Please apply following PR-related labels when appropriate:

• C0-breaking: if your change could break the existing client, e.g. API change, critical logic change
• C1-noteworthy: if your change is non-breaking, but is still worth noticing for the client, e.g. reference code improvement

How (Optional)

Testing Evidences

generate vc:

erc20(trx):

{
	context: ["https://www.w3.org/2018/credentials/v1", "https://w3id.org/security/suites/ed25519-2020/v1"],
	id: "0xdab1d8f33511e9ce4163fc39b069a7d1beed20d9cfb22819cacbe9287df7781c",
	types: [VerifiableCredential],
	credential_subject: CredentialSubject {
		id: "did:litentry:substrate:0x0000000000000000000000000000000000000000000000000000000000000000",
		description: "The amount of a particular token you are holding",
		types: "Token Holding Amount",
		assertion_text: "",
		data_source: None,
		assertions: [And {
			items: [Item {
				src: "$token",
				op: Equal,
				dst: "trx"
			}, Item {
				src: "$holding_amount",
				op: GreaterEq,
				dst: "1"
			}, Item {
				src: "$holding_amount",
				op: LessThan,
				dst: "50"
			}]
		}],
		values: [true],
		endpoint: ""
	},
	issuer: Issuer {
		id: "",
		name: "Litentry TEE Worker",
		mrenclave: "11111111111111111111111111111111",
		runtime_version: IssuerRuntimeVersion {
			parachain: 0,
			sidechain: 0
		}
	},
	issuance_date: "2024-06-13T12:22:46.826837967+00:00",
	parachain_block_number: 0,
	sidechain_block_number: 0,
	proof: None,
	credential_schema: CredentialSchema {
		id: "https://raw.githubusercontent.com/litentry/vc-jsonschema/main/dist/schemas/25-token-holding-amount/1-1-0.json",
		types: "JsonSchemaValidator2018"
	}
}

native token(bnb):

{
	context: ["https://www.w3.org/2018/credentials/v1", "https://w3id.org/security/suites/ed25519-2020/v1"],
	id: "0x8dc62b246d69406a82c1d2500904480299a1afccbca20b017b7ebb50dabe967e",
	types: [VerifiableCredential],
	credential_subject: CredentialSubject {
		id: "did:litentry:substrate:0x0000000000000000000000000000000000000000000000000000000000000000",
		description: "The amount of a particular token you are holding",
		types: "Token Holding Amount",
		assertion_text: "",
		data_source: None,
		assertions: [And {
			items: [Item {
				src: "$token",
				op: Equal,
				dst: "bnb"
			}, Item {
				src: "$holding_amount",
				op: GreaterEq,
				dst: "1"
			}, Item {
				src: "$holding_amount",
				op: LessThan,
				dst: "50"
			}]
		}],
		values: [true],
		endpoint: ""
	},
	issuer: Issuer {
		id: "",
		name: "Litentry TEE Worker",
		mrenclave: "11111111111111111111111111111111",
		runtime_version: IssuerRuntimeVersion {
			parachain: 0,
			sidechain: 0
		}
	},
	issuance_date: "2024-06-13T12:22:46.834042701+00:00",
	parachain_block_number: 0,
	sidechain_block_number: 0,
	proof: None,
	credential_schema: CredentialSchema {
		id: "https://raw.githubusercontent.com/litentry/vc-jsonschema/main/dist/schemas/25-token-holding-amount/1-1-0.json",
		types: "JsonSchemaValidator2018"
	}
}

TODO: Add all tokens.
All tokens have been added, reference from rust code.

[linear]

P-845 BNB Token holding amount

P-846 ETH Token holding amount

[Kailai-Wang]

I browsed the whole structure, it seems to be well desigend and made, nicely done

We'll need @kziemianek and @higherordertech to check more details 🙌

[kziemianek]

I wanted it to have 1 function per 1 rpc method but that's fine too.

[0xverin]

It is not very convenient to use externally, and requires a lot of if statements, so I merged them here.

[kziemianek]

Can this be further simplified with #2812 ?
If yes then please wait for #2812 to be merged first.