refactor: replace pureCommentPlugin with __NO_SIDE_EFFECTS__ annotation

[hi-ogawa]

Just discovered __NO_SIDE_EFFECTS__ is being introduced in rollup then later esbuild followed up

• feat: support #__NO_SIDE_EFFECTS__ annotation for function declaration  rollup/rollup#5024
• Support #__NO_SIDE_EFFECTS__ comment from Rollup evanw/esbuild#3149

This can replace my super ad-hoc pureCommentPlugin:

ytsub-v3/remix.config.js

Lines 32 to 33 in 9d67042

	// tree-shake `export const loader = makeLoader(...)` from client bundle
	function pureCommentPlugin() {

[hi-ogawa]

Or we can go with another workaround and pureCommentPlugin will be irrelevant

• refactor: split server page exports + remove pureCommentPlugin #476