currentScript hook to try document.currentScript before lastScript

[jchip]

fix #2465

Adds a hook function getCurrentScript that try document.currentScript before getting the lastScript.

[github-actions]

File size impact

Merging main into main will impact 2 files in 1 group.

browser (2/2)

File	raw	gzip	brotli	Event
dist/s.min.js	+124 (8,006)	+37 (3,161)	+36 (2,868)	modified
dist/system.min.js	+124 (12,344)	+36 (4,758)	+24 (4,285)	modified
Total size impact	+248 (20,350)	+73 (7,919)	+60 (7,153)

node (0/1)

No impact on files in node group.

extras (0/8)

No impact on files in extras group.

_{Generated by file size impact during size-impact#6178313082}