Add gm float transformer

[agedemenli]

Introduce FloatTransformer which uses greenmasktransformers.RandomFloat64Transformer under the hood.

[eminano]

It might be less verbose (and maybe a bit more readable) to use the encoding/binary library.

var buf [8]byte
binary.BigEndian.PutUint64(buf[:], math.Float64bits(f))

https://stackoverflow.com/a/43696189

[github-actions]

Merging this branch changes the coverage (1 decrease, 1 increase)

Impacted Packages	Coverage Δ	🤖
github.com/xataio/pgstream/pkg/transformers	100.00% (ø)
github.com/xataio/pgstream/pkg/transformers/builder	14.81% (-1.85%)	👎
github.com/xataio/pgstream/pkg/transformers/greenmask	94.89% (+1.37%)	👍

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/xataio/pgstream/pkg/transformers/builder/transformer_builder.go	14.81% (-1.85%)	27 (+3)	4	23 (+3)	👎
github.com/xataio/pgstream/pkg/transformers/greenmask/greenmask_float_transformer.go	96.55% (+96.55%)	29 (+29)	28 (+28)	1 (+1)	🌟
github.com/xataio/pgstream/pkg/transformers/transformer.go	100.00% (ø)	7	7	0

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/xataio/pgstream/pkg/transformers/greenmask/greenmask_float_transformer_test.go