What type of PR is this?

/kind feature

What does this PR do / why do we need it:

We have created a component that can push some operators down to our component for calculation.OpenLookeng webUI's statistics is after our calculate, as shown in the following figure:
But we want to display the statistics before calculation. We add an API and modify the statistics method, as shown in ther following figure:

Which issue(s) this PR fixes:

Fixes #I53R9F:add API to get statistics from pageSource