Option to disable loading of existing source maps for the source

Created by: stof

The old gulp-sourcemaps had a loadMaps setting to control whether existing maps should be loaded. Gulp 4 has a single setting in gulp.src which controls both enabling sourcemaps and loading existing ones.

This cause issues for me when npm packages ship their bundle files with a sourcemap while they don't ship their original source code at the same time (and so they have sourcemaps pointing to non-existent files). For such cases, I'd rather have my own source maps point me to their bundle file (that I know about) rather than to their source code (that I don't know about). I would be great if this feature could be available again.

What version of gulp are you using? 4.0.2

What versions of npm and node are you using? node 12.14.1 yarn 1.21.1