feat: Support Adds in a Deep Subtree (cosmos#8)

* ICS23-style approach for DeepSubTree creation

* Fix deepsubtree, all checks pass

* Update documentation for deep subtrees

* Fix deepsubtree to accomodate left/right paths both

* Refactor test code

* Refactor TestDeepSubtreeStepByStep

* Address comments

* Refactor code

* Disable gocritic and unused

* Add description

* Refactor code to check err in Set

* Modify traversal conditions to be clearer

* feat: build deep subtree from ICS23 inclusion proofs (cosmos#9)

* feat: build deep subtree from ICS23 inclusion proofs

* feat: handle non-existence proofs

* linter: goimports deepsubtree.go

* refactor: addExistenceProofProof -> addExistenceProof

* fix: un-hardcode size of byte array

* Add more comments

* Refactor ndb.Commit call outside for loop

* verify that in the case that dst.root != nil that the root node hash matches the provided hash and check dst.root != nil first

* Add strings and use strings.Repeat

* Delete addPath and AddPath

* Remove print statements

* Refactor recomputeHash usage

Co-authored-by: Matthew Sevey <[email protected]>

* return err directly

Co-authored-by: Matthew Sevey <[email protected]>

* Address linting checks

* Use tm-db instead of cosmos-db

* Fix linter

* Add test to check add operation in deepsubtree: WIP

* Add insert key functionality WIP

* Try replicating non-inclusion proofs

* Add sibling nodes to nonExistenceProofs

* Refactor test code

* Finish adding add functionality to dst

* Add Remove functionality to dst

* Fix linting errors

* Fix GetSiblingNode

* Remove more print statements

* Add comment for each case in recursive set

* Change which methods are exported and document exported methods

* feat: Support Empty Hashes and Add constructor (cosmos#11)

* Export siblings

* Add deepsubtree constructor

* Support empty root hashes

* Use working hash instead of root.hash

* Use tm-db instead of cosmos-db

* Return nil in BuildTree

* Address comments

* Address more comments

Co-authored-by: Tomasz Zdybał <[email protected]>
Co-authored-by: Matthew Sevey <[email protected]>