Refactor DocumentEncode & Document Bytes Conversion

[sarvalabs-manish]

Document Encoding Refactor

• Fixes Undecodable Document Wire for Document.Bytes() #11
• Refactored DocumentEncode() function to return a Document instead of an encoded []byte.
• Extended the Polorize function to check if the object to be encoded is a Document and if it is, it will cheaply pack it and create a document-encoded wire tagged with WireDoc. Now the correct way to encode a struct into a document-encoded wire is follows:

document, err := DocumentEncode(object)
if err != nil {
    log.Fatal(err)
}

// This is the best way to collapse a Document into its wire form
converted := document.Bytes()

// This is also a valid way, and is the same functionality invoked by the Bytes()
// method but the error check is not necessary as the conversion is safe.
encoded, err := Polorize(document)
if err != nil {
    log.Fatal(err)
}

// Both options generate the exact same wire and take the same 
// amount of time. It is only a matter of syntactic sugar.
fmt.Println(bytes.Equal(converted, encoded))

// Output:
// true

• Updated Document test cases and examples for new syntax of DocumentEncode
• Updated BenchmarkDocument for new syntax of DocumentEncode

[sarvalabs-rahul]

LGTM 👏