Add Token Transfer Processor

[aditya1702]

What

Add a token transfer processor that uses the corresponding ttp processor to extract debit/credit events. Once the events are extracted, the processor generates state changes with the appropriate information (account ID, operation ID, tx hash, claimable balance ID etc....).

Note: only DEBIT, CREDIT, MINT and BURN state changes are generated.

The following operations are processed:

• CreateAccount
• AccountMerge
• Payment
• CreateClaimableBalance
• ClaimClaimableBalance
• Clawback, ClawbackClaimableBalance
• LiquidityPoolDeposit, LiquidityPoolWithdraw
• PathPaymentStrictSend, PathPaymentStrictReceive
• ManageBuyOffer, ManageSellOffer
• InvokeHostFunction (SEP-41)

The unit tests build a transaction for each case and asserts the proper creation of transfer events.

Why

Part of the state change indexer work

Known limitations

N/A

Issue that this PR addresses

Closes #194

Checklist

PR Structure

• It is not possible to break this PR down into smaller PRs.
• This PR does not mix refactoring changes with feature changes.
• This PR's title starts with name of package that is most changed in the PR, or all if the changes are broad or impact many packages.

Thoroughness

• This PR adds tests for the new functionality or fixes.
• All updated queries have been tested (refer to this check if the data set returned by the updated query is expected to be same as the original one).

Release

• This is not a breaking change.
• This is ready to be tested in development.
• The new functionality is gated with a feature flag if this is not ready for production.

[marcelosalloum]

Looking great so far 👏