Backport the 0.5.x kde icon and the shape of the RowEditorContextMenu

static/plugin_dbui/resources/css/kde-oxygen.css

...c/plugin_dbui/resources/icons/oxygen/application-exit.png

static/plugin_dbui/resources/icons/oxygen/archive-insert.png

static/plugin_dbui/resources/icons/oxygen/archive-remove.png

static/plugin_dbui/resources/icons/oxygen/dialog-close.png

static/plugin_dbui/resources/icons/oxygen/document-new.png

static/plugin_dbui/resources/icons/oxygen/edit-copy.png

static/plugin_dbui/resources/icons/oxygen/edit-cut.png

static/plugin_dbui/resources/icons/oxygen/edit-delete.png

static/plugin_dbui/resources/icons/oxygen/edit-rename.png

...in_dbui/resources/icons/oxygen/edit-text-frame-update.png

static/plugin_dbui/resources/icons/oxygen/folder-yellow.png

static/plugin_dbui/resources/icons/oxygen/folder.png

static/plugin_dbui/resources/icons/oxygen/tab-close.png

static/plugin_dbui/resources/icons/oxygen/text-field.png

...ic/plugin_dbui/resources/icons/oxygen/view-form-table.png

static/plugin_dbui/resources/icons/oxygen/view-form.png

static/plugin_dbui/resources/icons/oxygen/window-close.png

static/plugin_dbui/src/appgridroweditorcontextmenu.js

views/plugin_dbui/debug.html