Allow setting additional MIME-Types / file extensions that will be returned in single-page-app

[RianFuro]

Start from the Use-case

The single-page-app construct sets a CloudFront function that tests for file extensions that will pass, redirecting all other requested files to the SPA Root:
https://github.com/getlift/lift/blob/fc97b0be0a340a85c86580cdd4adb5ac002a7a92/src/constructs/aws/SinglePageApp.ts#L48C9-L60C4

I'd like to serve .babylon files as well. However, without any ability to customize this whitelist, I'd have to go quite the way around the construct just to allow this.
Would it be in scope for lift to add a configuration option to extend the list of permitted extensions?

Example Config

constructs:
  spa:
    type: single-page-app
    allowedFiletypes:
      - babylon

Implementation Idea

Aside from adding a configuration option, the change should be quite straight forward, as we'd just need to modify the cf-function slightly:

+        let extraFiletypes = configuration.allowedFiletypes.join('|')
+        if (extraFiletypes) extraFiletypes = '|' + extraFiletypes
-        const code = `var REDIRECT_REGEX = /^[^.]+$|\\.(?!(css|gif|ico|jpg|jpeg|js|png|txt|svg|woff|woff2|ttf|map|json|webp|xml|pdf|webmanifest|avif|wasm)$)([^.]+$)/;
+        const code = `var REDIRECT_REGEX = /^[^.]+$|\\.(?!(css|gif|ico|jpg|jpeg|js|png|txt|svg|woff|woff2|ttf|map|json|webp|xml|pdf|webmanifest|avif|wasm${extraFiletypes})$)([^.]+$)/;


function handler(event) {
    var uri = event.request.uri;
    var request = event.request;
    var isUriToRedirect = REDIRECT_REGEX.test(uri);


    if (isUriToRedirect) {
        request.uri = "/index.html";
    }${additionalCode}


    return event.request;
}`;

[RianFuro]

Would probably also solve for #426 without any additional code changes.