Merge pull request #2166 from ProjectMirador/2098-remove-plugin-related-things

__tests__/integration/mirador/plugins.html

__tests__/integration/mirador/plugins.test.js

__tests__/src/components/CompanionWindowFactory.test.js

__tests__/src/components/WindowSideBar.test.js

__tests__/src/components/WorkspaceControlPanel.test.js

__tests__/src/lib/componentPlugins.test.js

src/containers/CompanionWindow.js

src/containers/OpenSeadragonViewer.js

src/containers/PrimaryWindow.js

src/containers/ThumbnailNavigation.js

src/containers/ViewerNavigation.js

src/containers/WindowSideBar.js

src/containers/WindowSideBarButtons.js

src/containers/WindowSideBarInfoPanel.js

src/containers/WindowThumbnailSettings.js

src/containers/WindowTopBar.js

src/containers/WindowTopBarButtons.js

src/containers/WindowTopMenu.js

src/containers/WindowTopMenuButton.js

src/containers/WindowViewSettings.js