Rebrand various CI scripts and modules

This replaces Riot with Element in various CI scripts, modules, parameters, etc.
This _should_ be the last major rebranding pass (hopefully).

Fixes https://github.com/vector-im/element-web/issues/14894

test/end-to-end-tests/element/install.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+set -e
+ELEMENT_BRANCH=develop
+
+if [ -d $BASE_DIR/element-web ]; then
+    echo "Element is already installed"
+    exit
+fi
+
+curl -L https://github.com/vector-im/element-web/archive/${ELEMENT_BRANCH}.zip --output element.zip
+unzip -q element.zip
+rm element.zip
+mv element-web-${ELEMENT_BRANCH} element-web
+cd element-web
+yarn install
+yarn run build