fix(platform-fastify): adds missing chaining API types for LightMyRequest inject()

[squareloop1]

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

If we currently use inject() from LightMyRequest to test the application we need to call it like this:

const response = await app.inject({ method: 'POST', url: '/login', payload: loginPayload });

If we try to use the chaining API we are getting TypeScript errors like TS2554: Expected 1 arguments, but got 0. because of missing types.

What is the new behavior?

With the chaining API (https://github.com/fastify/light-my-request#method-chaining) we can also call it in a fluent style like this:

const response = await app.inject().post('/login').payload(loginPayload).end()

Types for this were missing, this PR adds the missing types to be able to use the chaining API. It also allows a usage which is more in line with other testing libraries like e.g. supertest.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[coveralls]

Pull Request Test Coverage Report for Build d391710a-b735-4cea-8768-6147c05fcad8

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.825%

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Totals
Change from base Build cf4f5692-9ee1-4371-8130-5c6f9c02faac:	0.0%
Covered Lines:	4929
Relevant Lines:	5198

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💛 - Coveralls

[kamilmysliwiec]

Thanks!