feat: extracting transaction witness

[bkioshn]

Description

Extracting transaction witness

Related Issue(s)

List the issue numbers related to this pull request.

Closes #326

Description of Changes

• Create a new dash map where key is the witness publickey hash using blake2b with size 24 and the value is the actual public key and the transaction number that this witness exist.
• A function to check whether the hash is in the provided tx number.
• A function to get the actual public key from the hash.
• Test case for Alonzo block is provided.

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream module

[stevenj]

Looks good, just some small changes requested

[stevenj]

LGTM