DX improvements for third-party script developers

[Kwack-Kwack]

Ok, lets try this again...

Goals

GM Compatibility

• @grant headers for GM_*, GM.* and PDA_* API access, as well as ###PDA-APIKEY### replacement. Requires notice for developers - this is a breaking change.
• @require header support
• Proper @match URL matching, rather than just a raw substring check
• Full GM_* and GM.* compatibility with ViolentMonkey where possible. ViolentMonkey is open-source, whereas modern TamperMonkey is not, therefore it will be much easier to achieve full compat here
• Proper version matching as per ViolentMonkey rather than loose string matching on invalid MAJOR.MINOR.MATCH

Script Installation

• Improved userscript detection for the install widget
• Better script update checks - once an hour?
• Options for how to handle new versions - notify / auto update / update icon / don't auto-check.
• Some form of "hot reload" for development. Must not auto-refresh the page on changes, as this is against the current scripting rules. Perhaps a toast, or just reload on each page load.
• Warn user of @grant headers with a basic breakdown.

Runtime

• Ability to connect to an external device for devtools
• Widget with currently running scripts and registered menu commands
• Better handling of serialisables in the console (fix [object Object] if possible)
• Show the source of logs in the console if possible, at least when originating from scripts themselves (override the native console object?)

Documentation

• Requirements for the script install widget
• Steps for external devtools
• PDA_* API
• Hot reload

Currently a list of features that would be desirable. Some (GM_* compat) are more important than others (hot reload).