* dsproxy: adds support for url params for plugin routes

* docs: fixes after review

* pluginproxy: rename Params to URLParams

* Update pkg/plugins/app_plugin.go

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

* Apply suggestions from code review

Co-Authored-By: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>
Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

* pluginproxy: rename struct

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>
Co-authored-by: Diana Payton <52059945+oddlittlebird@users.noreply.github.com>