Replace Riot with Element in docs and comments

This only covers the simple cases of references to issues and repos. More
complex areas, such as deployment scripts, will be handled separately.

Part of https://github.com/vector-im/element-web/issues/14864

scripts/ci/end-to-end-tests.sh

@@ -13,7 +13,7 @@ handle_error() {
 
 trap 'handle_error' ERR
 
-echo "--- Building Riot"
+echo "--- Building Element"
 scripts/ci/layered-riot-web.sh
 cd ../riot-web
 riot_web_dir=`pwd`

scripts/gen-i18n.js

@@ -217,7 +217,7 @@ function getTranslationsOther(file) {
 
     const trs = new Set();
 
-    // Taken from riot-web src/components/structures/HomePage.js
+    // Taken from element-web src/components/structures/HomePage.js
     const translationsRegex = /_t\(['"]([\s\S]*?)['"]\)/mg;
     let matches;
     while (matches = translationsRegex.exec(contents)) {