Add JwtModule datasource

[iamacook]

Summary

This adds the JwtModule datasource as part of a test implementation for SiWe authentication, breaking down #1321 for review.

It leverages the jsonwebtoken package which is the "highest up" the dependency tree for JWT management, not requiring manual interfacing with signatures.

Changes

• Add JWT_ISSUER and JWT_SECRET env. vars.
• Add JwtModule/JwtService, adhering to IJwtService:
  • sign accepts a payload and date validity options, explicitly adding the secret and issuer.
  • verify accepts a payload, explicitly adding the secret and issuer.
• Appropriate test coverage for the above.

[coveralls]

Pull Request Test Coverage Report for Build 8537310941

Details

• 9 of 16 (56.25%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.09%) to 93.051%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/datasources/jwt/jwt.service.interface.ts	0	1	0.0%
src/datasources/jwt/jwt.module.ts	0	6	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/routes/transactions/entities/tests/human-description.builder.ts	3	60.0%

Totals
Change from base Build 8525317361:	-0.09%
Covered Lines:	6499
Relevant Lines:	6735

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💛 - Coveralls