Make the toolchain overriding config hierarchical #313

	name: AllFeatures (PR)

	# This is an additional workflow to test building with all feature combinations.
	# Unlike our main workflows, this doesn't self-test the rustup install scripts,
	# nor run on the rust docker images. This permits a smaller workflow without the
	# templating and so on.

	on:
	pull_request:
	branches:
	- "*"
	- renovate/*

	jobs:
	build:
	name: Build
	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	matrix:
	# Might add more targets in future.
	target:
	- x86_64-unknown-linux-gnu
	steps:
	- name: Clone repo
	uses: actions/checkout@v4
	- name: Install rustup stable
	run: rustup toolchain install stable --profile minimal
	- name: Install Protoc
	uses: arduino/setup-protoc@v1
	with:
	version: "3.x"
	repo-token: ${{ secrets.GITHUB_TOKEN }}
	- name: Set environment variables appropriately for the build
	run: \|
	echo "$HOME/.cargo/bin" >> $GITHUB_PATH
	echo "TARGET=${{ matrix.target }}" >> $GITHUB_ENV
	- name: Cache Cargo
	uses: Swatinem/rust-cache@v2
	- name: Install cargo-all-features
	run: cargo install cargo-all-features --git https://github.com/rbtcollins/cargo-all-features.git
	- name: Ensure we have our goal target installed
	run: \|
	rustup target install "$TARGET"
	- name: Build every combination
	run: \|
	cargo check-all-features --root-only

Provide feedback