improve performance and fix regex reset .proxy.js imports

[dnikku]

Hi, i improved performance of regex (start line with ^import); In my project, where I use vuetify, on file 'vuetify.css.proxy.js' it took more than 10 minutes ...
and i fixed (make it multiline "/mg") for scenarios when the import "...proxy.js" is not on the first line.

[KonnorRogers]

hmm...I think making it multiline isnt a bad idea, I worry about possibly being too open and letting bugs slip in with this implementation. Ideally theres an AST parser to detect imports...anyways, by using /^import/ it'll miss if a user does: await import

[dnikku]

AST it is ideal as you said, but not necessary ...
The big problem is the regex goes into "catastrophic backtracking" (see: https://community.appway.com/screen/kb/article/checking-strings-avoiding-catastrophic-backtracking-1482810891360).

a better regex is: /import\s+['"].+.(\w+).proxy.js['"]/mg

ironically the problem occurs in a file like something.ext.proxy.js file, maybe it is better to ignore these files, too!

index.js (line 154)
// Rewrite "proxy.js" imports prior to building
glob
.sync(buildDirectory + "/**/*.js", { nodir: true })
.filter(file => !file.endsWith(".proxy.js")) // Added this filter
...

Snippet from the vuetify.css.proxy.js (has 650KB and only 10 lines): Catastrophic backtracking happend on import(ant) ...

// [snowpack] add styles to the page (skip if no document exists)
if (typeof document !== 'undefined') {
const code = ".theme--light.v-application {\n background: #FFFFFF;\n color: rgba(0, 0, 0, 0.87);\n}\n.theme--light.v-application .text--primary {\n color: rgba(0, 0, 0, 0.87) !important;\n}\n.theme--light.v-application .text--secondary {\n color: rgba(0, 0, 0, 0.6) !important;\n}\n.theme--light.v-application .text--disabled {\n color: rgba(0, 0, 0, 0.38) !important;\n}\n\n.theme--dark.v-application {\n bac ...