Don't use distinct `run`s per compile target

[jsoref]

github/codeql-action#1058 (comment)

[d-winsor]

Analysis runs inside the compiler, so the analysis tool is actually being run as many times as there are compile targets. We can have the javascript merge the SARIF content into one run to work-around this.

The limitation of number of runs feels a little arbitrary given the flexible nature of SARIF but GitHub Code Scanning is the main selling point of the action so I will update the tool to merge the results into a single run.

[jsoref]

Hey, I'm not endorsing this or any other arbitrary limit :). You're welcome and perhaps even encouraged to talk to that other MS division about it.

(I'm in the process of setting up my own sarif generation and am hitting all sorts of fun edges...)

Anyway, thanks for taking this on.