Send batch of XAPI statements

[lunika]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.

For each XAPI statements created in Marsha, a call to a LRS can be made. XAPI activity can be very intensive and result in DDOSing the LRS.

Describe the solution you'd like

Send XAPI statements by batch of X records to divide the number of fetch to the LRS.
Statements can be stored in redis and send every X records.