Feat/#1752 fix witness generation - json exportor

[KimiWu123]

Description

closed #1752

Issue Link

#1752

Type of change

• [x] New feature (non-breaking change which adds functionality)

Contents

• This PR merged .go files of #1756.
• Have a new function, GenerateWitness to export json for stack trie.
• Add isTxProof flag in equipLeafWithModExtensionNode and `addBranchAndPlaceholder' to avoid touching the exising logic of the state trie.
• Fix GetProof(): before this fix, if any hashed nodes in the proof, other non-hashed nodes will not append to the proof. This causes the output proofs are incorrect.
• Add nibbles and proof type in StackProof for exporting json files.
• Modified extension node is not included in this PR, will do it in futher PR. #1809

[KimiWu123]

Hi @miha-stopar, I merged #1756, but only .go files, and now everything works, all the tests were passed! It' ready for review .