feat(bindings/go): add benchmark.

[yuchanns]

Part of #4892. Add a benchmark.

Here is a benchmark between new and old implementations with the same benchmark read and write behavior in backend memory:

purego+libffi (as new.txt)

goos: linux
goarch: arm64
pkg: github.com/apache/opendal/bindings/go
BenchmarkWrite4KiB-10            1000000              2844 ns/op
BenchmarkWrite256KiB-10           163346             10092 ns/op
BenchmarkWrite4MiB-10              12900             99161 ns/op
BenchmarkWrite16MiB-10              1785            658210 ns/op
BenchmarkRead4KiB-10              194529              6387 ns/op
BenchmarkRead256KiB-10             14228             82704 ns/op
BenchmarkRead4MiB-10                 981           1227872 ns/op
BenchmarkRead16MiB-10                328           3617185 ns/op
PASS
ok

CGO (as old.txt)

go test -bench=. -tags dynamic .
goos: linux
goarch: arm64
pkg: opendal.apache.org/go
BenchmarkWrite4KiB-10             241981              4240 ns/op
BenchmarkWrite256KiB-10           126464             10105 ns/op
BenchmarkWrite4MiB-10              13443             89578 ns/op
BenchmarkWrite16MiB-10              1737            646155 ns/op
BenchmarkRead4KiB-10               53535             20939 ns/op
BenchmarkRead256KiB-10              9008            132738 ns/op
BenchmarkRead4MiB-10                 576           1846683 ns/op
BenchmarkRead16MiB-10                230           6305322 ns/op
PASS
ok

Diff with benchstat

benchstat old.txt new.txt
goos: linux
goarch: arm64
pkg: github.com/apache/opendal/bindings/go
               │   new.txt    │
               │    sec/op    │
Write4KiB-10     2.844µ ± ∞ ¹
Write256KiB-10   10.09µ ± ∞ ¹
Write4MiB-10     99.16µ ± ∞ ¹
Write16MiB-10    658.2µ ± ∞ ¹
Read4KiB-10      6.387µ ± ∞ ¹
Read256KiB-10    82.70µ ± ∞ ¹
Read4MiB-10      1.228m ± ∞ ¹
Read16MiB-10     3.617m ± ∞ ¹
geomean          90.23µ
¹ need >= 6 samples for confidence interval at level 0.95

pkg: opendal.apache.org/go
               │   old.txt    │
               │    sec/op    │
Write4KiB-10     4.240µ ± ∞ ¹
Write256KiB-10   10.11µ ± ∞ ¹
Write4MiB-10     89.58µ ± ∞ ¹
Write16MiB-10    646.2µ ± ∞ ¹
Read4KiB-10      20.94µ ± ∞ ¹
Read256KiB-10    132.7µ ± ∞ ¹
Read4MiB-10      1.847m ± ∞ ¹
Read16MiB-10     6.305m ± ∞ ¹
geomean          129.7µ
¹ need >= 6 samples for confidence interval at level 0.95

What a surprise!

[Xuanwo]

Thanks a lot!