Add support for Fastify (2)

[timokoessler]

Based on #246, but uses new hook system #324.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.00000% with 20 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
library/sources/Fastify.ts	93.78%	10 Missing :warning:
library/sources/fastify/wrapHandler.ts	72.72%	9 Missing :warning:
library/sources/fastify/contextFromRequest.ts	96.15%	1 Missing :warning:

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