Should not modify case of node types when displaying non-Skyframe graphs

[benradf]

Problem
For Skyframe graphs, node types look LIKE_THIS in the database (which is how bazel dump shows them). Whereas in the frontend they are displayed in camel case with the underscores removed, LikeThis. Now that Skyscope supports importing arbitrary Graphviz graphs, this transformation is causing node types to be rendered in unexpected ways.

Solution
Instead of having node types transformed by the frontend just before displaying them, we should instead transform them during the import process and have the frontend display exactly what it received from the backend. The node type prefix should also be stripped from the rest of the node data, and the filter endpoint updated to search the concatenation of both. Together these changes will make Skyscope more suitable for general purpose use.