Namespace stripped from sourcemap sources in v0.25.0

[bep]

In Hugo we have some custom import resolvers similar to:

build.OnResolve(api.OnResolveOptions{Filter: `.*`},
build.OnLoad(api.OnLoadOptions{Filter: `.*`, Namespace: "mynamespace"},

With the above, there's no way for esbuild to build the correct source maps without additional information, so we adjust the sourcemaps generated by esbuild by looking at the namespace prefix. This worked great in v0.24.0.

In v0.25.0, without that prefix, we have no (simple) way of knowing where to look.