[keyserver] modified createMessages function to handle inserting targetMessageID into the DB

Summary:
modified createdMessages function to handle inserting targetMessageID into the DB. For these changes, I needed to check if a targetMessageID existed on the messageData object, if it did assign it to the targetMessageID variable otherwise assign targetMessageID to null. Then we wanted to modify the messageInsertQuery to handle setting targetMessageID to target_message in the db

Linear Task: ENG-2246

Test Plan:
Please see the screenshots below to see what the reaction message looks like in the db. For this example I liked the message "as you inevitably discover bugs, have feature requests..."

Reviewers: atul, rohan, tomek, ashoat

Reviewed By: atul, tomek, ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D5747