refactor: prepare vue components for vapor mode (#38798)

Removes what would block a later switch to Vue's vapor mode:
`vue-chartjs` and the `SvgIcon` render function are virtual DOM
components, and `v-memo` has no vapor equivalent. This does not adopt
vapor mode, which will be stable in upcoming Vue 3.6.

`vue-chartjs` was a thin wrapper over chart.js, so a local
`ChartCanvas.vue` replaces it. Chart data and options move into computed
values to keep their object identity, which is what `v-memo` was
compensating for.

`chartjs-adapter-dayjs-4` is moved first-party, just ~40 lines that are
easy to maintain.

web_src/js/components/SvgIcon.test.ts

@@ -0,0 +1,10 @@
+import SvgIcon from './SvgIcon.vue';
+import {createApp, h} from 'vue';
+
+test('SvgIcon', () => {
+  const root = document.createElement('div');
+  createApp({render: () => h(SvgIcon, {name: 'octicon-dot-fill', size: 24, class: 'base', symbolId: 'svg-symbol-dot'})}).mount(root);
+  expect(root.innerHTML).toBe(
+    `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="24" height="24" aria-hidden="true" class="svg octicon-dot-fill tw-hidden svg-symbol-container base"><symbol id="svg-symbol-dot" viewBox="0 0 16 16"><path d="M8 4a4 4 0 1 1 0 8 4 4 0 0 1 0-8"></path></symbol></svg>`,
+  );
+});