Experimental implementation for webapp plugins (#7185)

* Start of experimental implementation for webapp plugins

* Updates to webapp plugin architecture

* Update pluggable test

* Remove debug code

webapp/yarn.lock

@@ -5063,9 +5063,9 @@ math-expression-evaluator@^1.2.14:
   version "1.2.16"
   resolved "https://registry.yarnpkg.com/math-expression-evaluator/-/math-expression-evaluator-1.2.16.tgz#b357fa1ca9faefb8e48d10c14ef2bcb2d9f0a7c9"
 
-mattermost-redux@mattermost/mattermost-redux#webapp-4.1:
+mattermost-redux@mattermost/mattermost-redux#master:
   version "0.0.1"
-  resolved "https://codeload.github.com/mattermost/mattermost-redux/tar.gz/31bb5c2f21b504c4b7cab6624e4884bd3fc9f294"
+  resolved "https://codeload.github.com/mattermost/mattermost-redux/tar.gz/c5a9c96468cb8099230c447c87f2ca630bbfb531"
   dependencies:
     deep-equal "1.0.1"
     harmony-reflect "1.5.1"