test_runner: calculate executed lines using source map
Fixes https://github.com/nodejs/node/issues/52775#issuecomment-2131456060 Supersedes https://github.com/nodejs/node/pull/53153
before this fix, the lines that were actually executed were calculated using the source file on the disk - this is not the case when using ES loaders/transpilers. since we don't need the actual code run we create fake lines with a dummy char, just to map the dummy line to its original source