Add remote server cross compilation (#19136)

This will allow us to compile debug builds of the remote-server for a
different architecture than the one we are developing on.

This also adds a CI step for building our remote server with minimal
dependencies.

Release Notes:

- N/A

Dockerfile-cross

@@ -0,0 +1,17 @@
+# syntax=docker/dockerfile:1
+
+ARG CROSS_BASE_IMAGE
+FROM ${CROSS_BASE_IMAGE}
+WORKDIR /app
+ARG TZ=Etc/UTC \
+    LANG=C.UTF-8 \
+    LC_ALL=C.UTF-8 \
+    DEBIAN_FRONTEND=noninteractive
+ENV CARGO_TERM_COLOR=always
+
+COPY script/install-mold script/
+RUN ./script/install-mold "2.34.0"
+COPY script/remote-server script/
+RUN ./script/remote-server
+
+COPY . .