Improve CI with proper test jobs + fmt/doc/clippy

Mainly imported from rustc-stable-hash CI[^1].

[^1]:
https://github.com/rust-lang/rustc-stable-hash/blob/cc85b7a5940308df8329d3812bc27dc0a2fd3a50/.github/workflows/rust.yml

.github/workflows/rust.yml

@@ -1,19 +1,73 @@
 name: Rust
 
+permissions:
+  contents: read
+
 on: [push, pull_request]
 
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: 1
+  RUSTUP_MAX_RETRIES: 10
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
 jobs:
-  build:
+  test:
+    strategy:
+      matrix:
+        os: [ubuntu, windows, macos]
     runs-on: ${{ matrix.os }}-latest
+    timeout-minutes: 30
     steps:
-    - uses: actions/checkout@v4
-    - uses: rust-lang/simpleinfra/github-actions/simple-ci@master
-    - name: "32-bit cross testing"
-      run: |
-        rustup toolchain install nightly
-        rustup override set nightly
-        rustup component add miri
-        cargo +nightly miri test --target i686-unknown-linux-gnu
+      - uses: actions/checkout@v4
+      - run: rustup default stable
+      - run: cargo check
+      - run: cargo test
+      - run: rustup default nightly
+      - run: cargo test --all-features
+  cross-test:
     strategy:
       matrix:
-        os: [ubuntu, windows, macos]
+        target: [
+            "x86_64-unknown-linux-gnu", # 64-bits, little-endian
+            "i686-unknown-linux-gnu", # 32-bits, little-endian
+            "mips-unknown-linux-gnu", # 32-bits, big-endian
+            "mips64-unknown-linux-gnuabi64", # 64-bits, big-endian
+          ]
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+      - name: install miri
+        run: rustup toolchain add nightly --no-self-update --component miri && rustup default nightly
+      - run: |
+          cargo miri test --target=${{ matrix.target }} --all-features
+        env:
+          MIRIFLAGS: -Zmiri-strict-provenance
+          RUSTDOCFLAGS: ${{ env.RUSTDOCFLAGS }} -Z randomize-layout
+          RUSTFLAGS: ${{ env.RUSTFLAGS }} -Z randomize-layout
+  fmt:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: rustup update stable && rustup default stable
+      - run: rustup component add rustfmt
+      - run: cargo fmt --all --check
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: rustup update stable && rustup default stable
+      - run: cargo doc --workspace --document-private-items --no-deps
+        env:
+          RUSTDOCFLAGS: -D warnings
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: rustup update stable && rustup default stable
+      - run: rustup component add clippy
+      - run: cargo clippy --workspace --all-targets --no-deps