Enable DevTools on Android

Is your feature request related to a problem? Please describe. For a web developer, it's helpful if we can inspect the website without using remote debugging or injecting userscripts like Eruda.

Describe the solution you'd like, including relevant patches or source

Looks like chromium already have basic support for this, so i made a patch to enable it by default, and add a menu item. (https://github.com/SimonShiki/thorium/commit/61a385404ca047a5a4d82d7d1ae25815233b0895)

The DevTools works fine on my tablet, with devtools chrome extension support. though the layout is too small on mobile.

Did you read the FAQ? https://thorium.rocks/faq yes i did