ci: Add clang build scripts

Adds scripts that instruct CI to build yuzu with the installed Clang
compiler on yuzuemu/build-environments:linux-fresh.

These scripts are based on the .ci/scripts/linux scripts, minus AppImage
building since that isn't necessary. Re-uses linux-fresh since that
container has Clang 12 installed.

.ci/scripts/clang/upload.sh

@@ -0,0 +1,20 @@
+#!/bin/bash -ex
+
+. .ci/scripts/common/pre-upload.sh
+
+REV_NAME="yuzu-linux-${GITDATE}-${GITREV}"
+ARCHIVE_NAME="${REV_NAME}.tar.xz"
+COMPRESSION_FLAGS="-cJvf"
+
+if [ "${RELEASE_NAME}" = "mainline" ]; then
+    DIR_NAME="${REV_NAME}"
+else
+    DIR_NAME="${REV_NAME}_${RELEASE_NAME}"
+fi
+
+mkdir "$DIR_NAME"
+
+cp build/bin/yuzu-cmd "$DIR_NAME"
+cp build/bin/yuzu "$DIR_NAME"
+
+. .ci/scripts/common/post-upload.sh