✨ v3 (feature): initial support for binding

[efectn]

Partially related: #1821

This PR aims to create detailed and moduler binding system for Fiber v3. Fiber ctx will be more clean thanks to this feature. Also Fiber will be able to bind into the map.

To-Do List:

• Embed bind into the DefaultCtx.
• Params binder.
• Resp header binder.
• Cookie binder.
• Add support for custom binders in automatically body binding.
• Support for map binding.
• Make Should/Must functional.
• Custom struct validator support.
• Add comment lines and simple README for binding.

Note: I won't change gorilla/schema in this PR. But next PRs, i'll create more minimal and useful parser for Fiber.

[trim21]

I have another idea and POC about this feature, we do not need internal temporary map and schema (or schema-lite), and gorilla/schema is really slow.

https://github.com/Trim21/inj/blob/master/example/main.go#L27

with go 1.18 generic, we can have a 2 allocs and good performance and (IMO) easy to use API like this:

app.Get("/:id", Wrap(func(c *fiber.Ctx, req Req) error {
	return c.JSON(req)
}))

and a 5 fields benchmark, (BenchmarkGorillaSchema_map_to_struct_only simple use schema to convert map to struct, not even contains code to build map from ctx)

cpu: AMD Ryzen 7 5800X 8-Core Processor
Benchmark_unmarshal_by_hand-16                          18636231                63.80 ns/op            0 B/op          0 allocs/op
Benchmark_lib_unmarshal-16                               6516075               183.0 ns/op            96 B/op          2 allocs/op
BenchmarkGorillaSchema_map_to_struct_only-16              435432              2818 ns/op             904 B/op         49 allocs/op
PASS

[efectn]

I have another idea and POC about this feature, we do not need internal temporary map and schema (or schema-lite), and gorilla/schema is really slow.

https://github.com/Trim21/inj/blob/master/example/main.go#L27

with go 1.18 generic, we can have a 2 allocs and good performance and (IMO) easy to use API like this:

app.Get("/:id", Wrap(func(c *fiber.Ctx, req Req) error {
	return c.JSON(req)
}))

and a 5 fields benchmark, (BenchmarkGorillaSchema_map_to_struct_only simple use schema to convert map to struct, not even contains code to build map from ctx)

cpu: AMD Ryzen 7 5800X 8-Core Processor
Benchmark_unmarshal_by_hand-16                          18636231                63.80 ns/op            0 B/op          0 allocs/op
Benchmark_lib_unmarshal-16                               6516075               183.0 ns/op            96 B/op          2 allocs/op
BenchmarkGorillaSchema_map_to_struct_only-16              435432              2818 ns/op             904 B/op         49 allocs/op
PASS

I checked your code and it seems good idea to use context methods instead of creating temporarily map. I'll check it in the next PR