integrate with RESTful backend to implement igorm math provider function

[info-it-best]

Expectation: 1) a POST endpoint that accepts exp:number and varNames: string[] 2) the endpoint does some validation and responds with an error or succeeds with structure like:

export type MathOperationResult = { goal: string result: string duration: number }

3) the response for Kordano Build in general will be different and for now is not yet developed 4) the POST endpoint should perform a few seconds maximum and it should also cache the results to respond faster net time.

[info-it-best]

5. backend should not serve more than one client at a time. If there is another request in process the client should get server is busy status immediately. And after a request is handle it should debounce next request for at least 1 second.