feat: add SignatureType type

[DaniSomoza]

What it solves

based on this suggestion: #1043

How this PR fixes it

export const SignatureTypes = {
  CONTRACT_SIGNATURE: 'CONTRACT_SIGNATURE',
  EOA: 'EOA',
  APPROVED_HASH: 'APPROVED_HASH',
  ETH_SIGN: 'ETH_SIGN'
} as const

export type SignatureType = (typeof SignatureTypes)[keyof typeof SignatureTypes]

[coveralls]

Pull Request Test Coverage Report for Build 12072824726

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 75.476%

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Totals
Change from base Build 12008934309:	0.02%
Covered Lines:	789
Relevant Lines:	974

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💛 - Coveralls