BIP44 support for flow.json defined keys

[bluesign]

On the way to close #600

Description

This PR adds ability to define account keys with BIP44 ( as defined in https://github.com/onflow/flow/blob/master/flips/20201125-bip-44-multi-account.md )

Example config:

"emulator-account": {
	"address": "f8d6e0586b0a20c7",
	"key": {
		"type": "bip44",
		"index": 0,
		"signatureAlgorithm": "ECDSA_P256",
		"hashAlgorithm": "SHA3_256",
		"mnemonic": "skull design wagon top faith actor valley crystal subject volcano access join",
		"derivationPath": "m/44'/539'/0'/0/0"
	}
}

• Derivation Path defaults to m/44'/539'/0'/0/0 if omitted.

If this is acceptable I will update the relevant documentation in this PR.

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[devbugging]

Nice! Just add comments otherwise LGTM

[devbugging]

@bluesign sorry I meant just add the documentation.

[devbugging]

Thank you! This is awesome.