References panel fetches highlighted file without %-decoding repo from URI

Created by: felixfbecker

Repro: https://k8s.sgdev.org/sourcegraph.visualstudio.com/Test%20Repo/-/blob/Test%20Folder/Test%20File.cs#L7:20&tab=references

The highlight request includes the % from the URI of the repo (interestingly not of the file):

We should add an extension integration test for this.