chacha20: add *Rng equivalence proptests with rand_core (#435)

This adds a proptest which generates a random seed and performs a
sequence of 16 random-sized reads from both RNGs, comparing them for
equivalence and ensuring they generate the same outputs.

Author: tarcieri

.github/workflows/chacha20.yml

@@ -75,6 +75,7 @@ jobs:
       - run: cargo check --target ${{ matrix.target }} --all-features
       - run: cargo test --target ${{ matrix.target }}
       - run: cargo test --target ${{ matrix.target }} --features zeroize
+      - run: cargo test --target ${{ matrix.target }} --all-features
 
   # Tests for the AVX2 backend
   avx2:
@@ -108,6 +109,7 @@ jobs:
       - run: cargo check --target ${{ matrix.target }} --all-features
       - run: cargo test --target ${{ matrix.target }}
       - run: cargo test --target ${{ matrix.target }} --features zeroize
+      - run: cargo test --target ${{ matrix.target }} --all-features
 
   # Tests for the SSE2 backend
   sse2:
@@ -141,6 +143,7 @@ jobs:
       - run: cargo check --target ${{ matrix.target }} --all-features
       - run: cargo test --target ${{ matrix.target }}
       - run: cargo test --target ${{ matrix.target }} --features zeroize
+      - run: cargo test --target ${{ matrix.target }} --all-features
 
   # Tests for the portable software backend
   soft:
@@ -174,6 +177,7 @@ jobs:
       - run: cargo check --target ${{ matrix.target }} --all-features
       - run: cargo test --target ${{ matrix.target }}
       - run: cargo test --target ${{ matrix.target }} --features zeroize
+      - run: cargo test --target ${{ matrix.target }} --all-features
 
   # Cross-compiled tests
   cross: