fix(scripts/build): use correct asset-copy paths on Windows

[DarianM]

Context

The copy plugin should be able to copy all the files correctly, regardless of the operating system (Windows, Linux, or macOS).

Closes #711 .

Changes proposed in this pull request

Convert the backslashes to forward slashes in the from and to paths passed to the copy plugin.

[github-actions]

Extension builds preview

Name	Link
Latest commit	421b623
Latest job logs	Run #11835264046
	Download
	Download

[sidvishnoi]

I wonder if we can directly use path.posix.join() instead to force forward slashes everywhere.

[DarianM]

@sidvishnoi
we can, but the issue is that path.posix.join() assumes all input paths are using forward slashes, but the input paths (SRC_DIR, DEV_DIR, DIST_DIR ) are actually provided by the operating system and nodejs, which means on windows they will contain backslashes.

// if we use path.posix.join():
path.posix.join(SRC_DIR, 'popup', 'index.html')
// results in: 'D:\\web-monetization-extension\\src/popup/index.html'
//  it doesn't convert the existing backslashes in the input paths

we can use path.posix directly, would first need to convert all input paths to use forward slashes from esbuild/config.ts like
export const SRC_DIR = path.resolve(ROOT_DIR, 'src').replaceAll(path.sep, path.posix.sep)

[sidvishnoi]

I think cleanest would be adding a util (say toPosix) and just call it to replace all windows separators to posix type, only for the copy plugin.

[sidvishnoi]

Perfect. Thanks @DarianM and congrats on your first PR here 🎉