Add support for new experimental sticky scroll feature

[attisan]

Feature description or problem with existing feature vscode recently introduced a sticky scroll feature (see https://dev.to/vscodetips/vs-code-tip-of-the-week-sticky-scroll-5f0o) to allow for better orientation within a possibly long file.

Describe the solution you'd like Currently this only seems to be supported by PHP IntelliSense but not by Intelephense (latter results in showing comment levels).