PR: Support for OBJECT ENCODING

[sashpawar11]

This PR adds support for OBJECT ENCODING and closes #964

Changes :

• Support added for OBJECT ENCODING subcommand, supporting the relevant encoding types available in dicedb.
• Integration tests cover all the cases in-depth.
• Unit test cases cover basic test coverage for the subcommand.

Note:

• The tests do not contain a case for the encoding type 'setint' ( ObjEncodingSetInt), as currently we do not encode sets as ints. We can add this case in the future when we integrate the functionality for encoding sets as ints.

Supported Object Types and Object Encoding:

Object Type	Object Encoding
string	raw
string	embstr
int	int
bytelist	deque
bitset	bf
json	json
bytearray	bytearray
set	setstr
set	setint
hashmap	hashmap
sortedset	btree

[sashpawar11]

Hi @lucifercr07 / @JyotinderSingh - please review the changes.
Thankyou.

[apoorvyadav1111]

Hey, thanks for the changes and adding support for new command OBJECT ENCODING. I have a suggestion regarding the eval.go changes. Would it be okay for us to use switch case rather than if statements to achieve the same.
Thanks

[sashpawar11]

Hey @lucifercr07 @JyotinderSingh @apoorvyadav1111 - closing this PR, my forked branch got slightly corrupted when merging too many new changes. Have create a new clean PR - #1039 and posted the new updates on it per suggestions provided here.