[@web/rollup-plugin-import-meta-assets] Add originalFileName to emitFile

[dmnsgn]

Relevant Rollup documentation

Note that when emitting assets that correspond to an existing file, it is recommended to set the originalFileName property in the this.emitFile call instead as that will not only watch the file but also make the connection transparent to other plugins.
Link

Change required

Add:

 const ref = this.emitFile({ 
   type: 'asset', 
   name: assetName, 
+  originalFileName: absoluteAssetPath,
   source: transformedAssetContents, 
 }); 

to this call:

web/packages/rollup-plugin-import-meta-assets/src/rollup-plugin-import-meta-assets.js

Lines 176 to 180 in b304034

	const ref = this.emitFile({
	type: 'asset',
	name: assetName,
	source: transformedAssetContents,
	});

Use case

Trying to map the source of some emitted assets in a plugin's writeBundle and getting null.

[bashmish]

I'd be happy to accept a PR with a fix for this, maybe some tests will need to be fixed, let me know if you need help