[DON'T MERGE] make client entry points explicit

[Rich-Harris]

Hit a bug on a decently-sized app where a chunk wasn't being created for one of the dynamically imported entry points representing a specific page. It's something to do with Rollup's code-splitting algo — if I remove certain imports from the page in question it gets chunked up correctly — but I don't have the bandwidth to delve too deeply into it.

Luckily I don't need to — we can just be explicit about what the entry points are. Bonus: in doing so we can make the file structure of the build much more navigable.

[Rich-Harris]

Whoops, must have fat-fingered Cmd-Enter or something before I finished writing the comment. This is marked 'don't merge' because it will conflict with #463, so I'm inclined to merge that first

[Rich-Harris]

the tests are passing! did the windows bug get fixed @GrygrFlzr or is it related to this PR somehow?!

[GrygrFlzr]

the tests are passing!

That's because it's broken something and is skipping a large number of tests entirely, if you take a look at the CI run: https://github.com/sveltejs/kit/pull/466/checks?check_run_id=2057620666

build:amp
 build:amp  vite v2.0.4 building for production...
✓ 0 modules transformed.
Could not resolve entry module (.svelte/build/runtime/internal/start.js).
Error: Could not resolve entry module (.svelte/build/runtime/internal/start.js).
    at error (D:\a\kit\kit\node_modules\.pnpm\rollup@2.40.0\node_modules\rollup\dist\shared\rollup.js:5279:30)
    at ModuleLoader.loadEntryModule (D:\a\kit\kit\node_modules\.pnpm\rollup@2.40.0\node_modules\rollup\dist\shared\rollup.js:18738:20)
    at async Promise.all (index 0) {
  code: 'UNRESOLVED_ENTRY',
  watchFiles: [
    'D:/a/kit/kit/packages/kit/test/apps/amp/src/routes/invalid/index.svelte',
    'D:/a/kit/kit/packages/kit/test/apps/amp/src/routes/valid/index.svelte',
    'D:/a/kit/kit/packages/kit/test/apps/amp/src/routes/valid/index.json.js'
  ]
}
(node:2936) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'close' of undefined
    at file:///D:/a/kit/kit/packages/kit/test/test.js:176:19
    at Number.runner (file:///D:/a/kit/kit/node_modules/.pnpm/uvu@0.5.1/node_modules/uvu/dist/index.mjs:90:29)
(node:2936) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:2936) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
transforming...

[Rich-Harris]

🙃 I thought it was too good to be true — thanks

[Rich-Harris]

I made the same changes in #463, so I'll close this