Generating the Template Code for Paystack using add_connector script

[jarnura]

Follow the steps outlined in the add_connector.md file. Execute the script provided in the markdown file with Connector name(eg: Paystack) and Connector base url. This will add respective code to add the specific connector in hyperswitch_connector crate.

• Do the changes according to the document in the files.

Then run the following commands:

• cargo clippy
• cargo +nightly fmt --all

Afterward, review the code and raise a pull request (PR).
Ref PR: #7285