Work around broken query parsing in merged configs

[exogen]

This works around a bug somewhere in webpack, another loader in the chain, or our config merging somehow.

In the webpack@1 version of extract-text-webpack-plugin, the loader chain must be a string, like so: css?foo!stylus?bar. It can't be a list of objects like so:

[{ loader: 'css', query: { ... } }, loader: 'stylus', query: { ... } }]

That means query options need to be serialized. For complex nested options, you're supposed to be able to do this, as demonstrated by @sokra:

"stylus?{ foo: 1, bar: 'two' }"
// or more conveniently:
"stylus?" + JSON.stringify(options)

This works in some versions of our archetype's webpack config. In others, we get this error:

ERROR in ./~/css-loader?-autoprefixer!./~/stylus-relative-loader?{"precacheImportVariables":[object Object]}!./client/styles/base.styl
Module build failed: SyntaxError: Unexpected 'o' at line 1 column 30 of the JSON5 data. Still to read: "object Object]}"
    at JSON5.parse.error (/Users/brianbeck/Projects/Walmart/product/node_modules/loader-utils/node_modules/json5/lib/json5.js:56:25)

Notice how the array gets turned into [object Object] – some module somewhere else in the chain is taking our perfectly fine JSON query, parsing it, then doing a terrible job re-serializating it, incorrectly, before it even gets to us.

So this PR introduces extra parsing of the precacheImportVariables option, which lets us specify it as a non-JSON query string by doing an extra parseQuery. 😠

/cc @ananavati @jmcriffey

[dstevensio]

This saddens me but I'm glad you worked around it.

LGTM 👍

[exogen]

We can eliminate this workaround by helping with this issue: Fitbit/webpack-config#45

[exogen]

Fixed in the latest webpack-config 6.1.3!