Fixes #878 .

Vue includes some built-in lifecycle events for VNodes. See:

• https://github.com/vuejs/core/blob/0b30b7d3be5185041b790286da8402dd10503dbb/packages/shared/src/general.ts#L86

These don't need to be declared by components, as they're implemented by Vue itself and aren't emitted manually.

Rather than rendering them as Undeclared, I've added a third state, Built-in:

While these lifecycle events are rarely used directly, Vue Router adds a vnode-unmounted listener to route components. Showing that listener as Undeclared is misleading, implying user error.

I've included a tooltip for the new state. I don't think there's currently any way to see that tooltip, as they aren't implemented in the UI, but I'll attempt a fix for that in a separate PR.

Side note: I tested this using the Vite plugin. I kept running into problems and eventually realised these were being caused by the Vue.js devtools Chrome extension. I wasn't intentionally using the Chrome extension, it just happened to be installed. My code was setting the values to Built-in and the extension was overwriting that with Undeclared. Once I realised I just disabled the extension, but the thought occurs that this sharing of data is likely to lead to compatibility problems more generally. I couldn't find this documented anywhere and it seems kinda scary that the extension can interfere like that.