gocbcore.EncodeCommonFlags ignores compression type when it generates flags

[peczenyj]

function gocbcore.EncodeCommonFlags totally ignores the compression type when it generates a flag object

example:

	flags := gocbcore.EncodeCommonFlags(gocbcore.JSONType, gocbcore.UnknownCompression)

	_, compression := gocbcore.DecodeCommonFlags(flags)

        fmt.Println("compressio is unknown?", compression == gocbcore.UnknownCompression) // returns false

https://go.dev/play/p/Tj7yqRWHHI6

[chvck]

Hi @peczenyj thanks for filing this issue. Is this an issue that you're actually facing in something that you're trying to do? There isn't actually a common flag value for unknown compression, as per https://github.com/couchbaselabs/sdk-rfcs/blob/master/rfc/0020-common-flags.md