Add sarif-diff to Code Scanning workflow

[mbaluda]

FIxes #57
Adds steps to the Code Scanning workflow checking that the new SARIF file matches the expected one stored in .github/workflows/javascript.sarif.expected.
If there is a mismatch, the new SARIF and a diff are uploaded as artefacts to eventually update the .expected file

Examples of passing and failing runs:
✅ https://github.com/advanced-security/codeql-sap-js/actions/runs/7787950054
❌ https://github.com/advanced-security/codeql-sap-js/actions/runs/7787745458

[rvermeulen]

Looks good overall.
If will change the structure in our restructuring PR to make it UI5 specific.

See the code comment for info on the request change.

[jeongsoolee09]

Code itself looks good, but does this mean we should keep javascript.sarif.expected updated?

[jeongsoolee09]

Also, it might be nice if we can replace Code Scanning / Analyze step with this one.

[mbaluda]

Code itself looks good, but does this mean we should keep javascript.sarif.expected updated?

Yes! After reviewing the diff, one would typically replace the SARIF with the one in the action artefacts like here:
https://github.com/advanced-security/codeql-sap-js/actions/runs/7787745458

adressed