#10: Feat - LFU cache implementation with approximate counting.

[Rits1272]

Fixes #10

• LFU cache eviction policy support in Dice

How LFU cache is implemented?

• The implementation is similar to Redis - details
• The access counter of a key is piggybacked to the LastAccessedAt field in Dice Obj defined here. The first 8 bits is allocated to maintaining the access counter and the last 24 bits are allocated to maintaining the last access time of a key
• The access counter is an approximate counter which is incremented logarithmically
• This PR does not include support for the decay mechanism as of yet.
• This LFU implementation do not add any additional memory footprint

Issue: #10

[Rits1272]

@JyotinderSingh please have a look. TIA!

[JyotinderSingh]

Thanks for introducing a new eviction algorithm to Dice @Rits1272! Please add comprehensive tests for these changes.

[arpitbbhayani]

@Rits1272 Please squash your commits before you push. You can do this once all changes are done.

[JyotinderSingh]

Hey @Rits1272, could you please address the comments and fix any conflicts? This PR has been open a while, let's try to get it merged.

[Rits1272]

@JyotinderSingh didn't get time this week, but will work on adding test cases, resolving conflicts and comments by this weekend

[Rits1272]

@JyotinderSingh apologies for the delay. I have added test cases, please review
Since the PR has gotten stale, there are many conflicts from previous commits. Can we use Squash and merge for this PR during merge to master?

[JyotinderSingh]

Thanks for adding support for LFU eviction algorithm, @Rits1272! The changes look good.
Approved