feat!: library rewrite

[metonym]

Closes #50, closes #44, closes #46, closes #53, closes #52, closes #48, closes #47, closes #46, closes #40, closes #26, closes #24, closes #19, closes #18, closes #17, closes #28

Breaking Changes

• Remove all preprocessors except for optimizeImports
• optimizeImports: drop support for carbon-icons-svelte version 10, carbon-pictograms-svelte version 10
• Rewrite optimizeCss plugin from scratch; it's now offered as a Vite/Rollup/Webpack plugin. carbon-components-svelte@0.85.0 or greater is required

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optimizeImports

• Completely re-written imports optimizer
• Only supports latest major versions of icons/pictgrams

Notes: for best DX, also instruct Vite to optimizeDeps.ignore

optimizeCss

• Vite/Rollup plugin, enforced in build phase

Steps:

The potential for false positives is too high (relying on any and all selectors). Instead, focus on class names as this is much more defensive (e.g., .bx--). The goal is to still remove the bulk of unused .bx-- selectors without needing to stress about false positives.

1. Pre-index the used class names per Carbon component.
2. Gather the resolved component names in the plugin.transform hook.
3. In the generateBundle hook, read in all generated .css files.
4. Traverse the CSS AST and remove all .bx-- selectors that are not included in the map.

[metonym]

What's blocking this PR is that some Carbon components that employ custom styling (e.g., HeaderSearch) does not correctly prune this.