Allow for custom npm packages in imported protos

Here is a link to the line where it speaks to our issue.
https://github.com/protocolbuffers/protobuf-javascript/blob/6113588085fea6149c51a750bd21b5cf9334a07d/generator/js_generator.cc#L116-L119

We currently make use of a variety of google protos other than those in the google-protobuf npm package. To make use of these, we have to explicitly include them in the npm package that we publish containing our generated protobufs. It would be ideal if we could publish the generated google protobufs we use in a separate npm package and use options in the .proto files to specify the name of the package to which these are published, and for this package to be used in the generated code whenever one of these protobufs is implemeneted. Similar to how this is for the "google-protobuf" imports

Beginne mit der im Issue verlinkten Datei generator/js_generator.cc in den Zeilen 116–119 und verfolge, wie Imports für google-protobuf ausgegeben werden. Ermittle, wie .proto-Optionen Paketnamen für andere generierte protobuf-Pakete angeben sollten; als abgeschlossen gilt die Aufgabe, wenn der generierte Code für die entsprechenden Imports die konfigurierten Paketnamen verwendet.