quote request api: shorten loading time

[chrtze]

because the quote request form is implemented as a lambda function, we need to wait for all steps of the function (create customer, create, finalize, download quote) to finish until we can return a response. we should refactor or rewrite this function to getting triggered and returning a response immediately and sending the quote in another process.

@peterkogo's idea: create a database entry for each quote request and then use hasura events for sending whenever something is inserted in the table.