Implements createrawtransaction RPC method and parameter validation. Tests to be added in follow-up commit.

Motivation

The goal of this PR is to implement the create_raw_transaction RPC endpoint for zebrad. This will support the effort to fully deprecate zcashd and enhance zcashd with all existing zcashd functionality. This PR will close the following issue: #8952

Specifications & References

Solution

• Adds createrawtransaction RPC implementation
• Adds parameter validation for inputs.
• Adds a test suite for createrawtransaction RPC method (Coming soon)

Tests

• Test will be added in the follow up commit as this is now a draft.

Follow-up Work

• There will be no follow up work for this pull request once it is completed.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.