Add window.loadFile and webContents.loadFile helper methods

[MarshallOfSound]

Closes #11560

[sindresorhus]

What do you think about the idea of adding a file option to BrowserWindow as a convenience? Most users will want to load the local file right away, so would be nice to be able to specify it there instead.

loadURL() is not a BrowserWindow option as it has support for its own options, but loadFile() only accepts a string, so it could easily be an option in BrowserWindow.

[sindresorhus]

Maybe also update the docs here: https://github.com/electron/electron/blame/249bd41e11443feb8949f21367eb1802b19f9544/docs/api/browser-window.md#L23 and here: https://github.com/electron/electron/blame/249bd41e11443feb8949f21367eb1802b19f9544/docs/api/web-contents.md#L1199

[MarshallOfSound]

What do you think about the idea of adding a file option to BrowserWindow as a convenience?

Not a fan tbh, I much prefer the explicit "create then navigate" approach we currently use. This method just makes it easier/safer for people to navigate to local files 👍

[MarshallOfSound]

Maybe also update the docs here:

Yeah once this goes through I'll follow up with a PR to update docs and usage in our own code. I didn't realize we had so much string templating loadURL around the place 🤔

[felixrieseberg]

Not a fan tbh, I much prefer the explicit "create then navigate" approach we currently use. This method just makes it easier/safer for people to navigate to local files 👍

I'm with you on that, especially because you can't attach listeners to something that hasn't been created yet - and therefore wouldn't be able to catch errors emitted via EventEmitter.

[codebytere]

I see a few things pending for future PRs in comments, but for the scope of this PR this looks good to me!