Make esbuild an optional peer dependency

[mrm007]

Prior art and discussions: #1018, #1171

esbuild is now a peer dependency in esbuild-plugin and esbuild-plugin-next.
Why make it a peer dependency? Because our script to bundle types bundles the Plugin type from esbuild into the output, which can cause a type error when consumers try to use it.
It's marked as optional, so it won't crash on install when consumers don't have esbuild in their dependencies.

I believe this is a better solution than both #1018 and #1171.
#1171 is too intrusive and adds esbuild everywhere, and consumers have to include it in their dependencies.
Relevant xkcd: https://xkcd.com/927/

Before

https://unpkg.com/browse/@vanilla-extract/[email protected]/dist/vanilla-extract-esbuild-plugin.cjs.d.ts (Plugin type is inlined)

After

import { IdentifierOption, CompileOptions } from '@vanilla-extract/integration';
import { Plugin } from 'esbuild';

interface VanillaExtractPluginOptions {
    outputCss?: boolean;
    /**
     * @deprecated Use `esbuildOptions.external` instead.
     */
    externals?: Array<string>;
    runtime?: boolean;
    processCss?: (css: string) => Promise<string>;
    identifiers?: IdentifierOption;
    esbuildOptions?: CompileOptions['esbuildOptions'];
}
declare function vanillaExtractPlugin({ outputCss, externals, runtime, processCss, identifiers, esbuildOptions, }?: VanillaExtractPluginOptions): Plugin;

export { vanillaExtractPlugin };

[changeset-bot]

🦋 Changeset detected

Latest commit: 74c37ce

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@vanilla-extract/esbuild-plugin-next	Patch
@vanilla-extract/esbuild-plugin	Patch

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