Use nextest for rust unittests (#6223)

## Problem
`cargo test` doesn't support timeouts 
or junit output format

## Summary of changes
- Add `nextest` to `build-tools` image
- Switch `cargo test` with `cargo nextest` on CI
- Set timeout

.config/nextest.toml

@@ -0,0 +1,2 @@
+[profile.default]
+slow-timeout = "1m"

.github/workflows/build_and_test.yml

@@ -339,16 +339,16 @@ jobs:
         run: |
           ${cov_prefix} mold -run cargo build $CARGO_FLAGS $CARGO_FEATURES --bins --tests
 
-      - name: Run cargo test
+      - name: Run rust tests
         run: |
-          ${cov_prefix} cargo test $CARGO_FLAGS $CARGO_FEATURES
+          ${cov_prefix} cargo nextest run $CARGO_FLAGS $CARGO_FEATURES
 
           # Run separate tests for real S3
           export ENABLE_REAL_S3_REMOTE_STORAGE=nonempty
           export REMOTE_STORAGE_S3_BUCKET=neon-github-ci-tests
           export REMOTE_STORAGE_S3_REGION=eu-central-1
           # Avoid `$CARGO_FEATURES` since there's no `testing` feature in the e2e tests now
-          ${cov_prefix} cargo test $CARGO_FLAGS --package remote_storage --test test_real_s3
+          ${cov_prefix} cargo nextest run $CARGO_FLAGS -E 'package(remote_storage)' -E 'test(test_real_s3)'
 
           # Run separate tests for real Azure Blob Storage
           # XXX: replace region with `eu-central-1`-like region
@@ -358,7 +358,7 @@ jobs:
           export REMOTE_STORAGE_AZURE_CONTAINER="${{ vars.REMOTE_STORAGE_AZURE_CONTAINER }}"
           export REMOTE_STORAGE_AZURE_REGION="${{ vars.REMOTE_STORAGE_AZURE_REGION }}"
           # Avoid `$CARGO_FEATURES` since there's no `testing` feature in the e2e tests now
-          ${cov_prefix} cargo test $CARGO_FLAGS --package remote_storage --test test_real_azure
+          ${cov_prefix} cargo nextest run $CARGO_FLAGS -E 'package(remote_storage)' -E 'test(test_real_azure)'
 
       - name: Install rust binaries
         run: |

Dockerfile.buildtools

@@ -151,6 +151,7 @@ RUN curl -sSO https://static.rust-lang.org/rustup/dist/$(uname -m)-unknown-linux
     cargo install cargo-hakari && \
     cargo install cargo-deny && \
     cargo install cargo-hack && \
+    cargo install cargo-nextest && \
     rm -rf /home/nonroot/.cargo/registry && \
     rm -rf /home/nonroot/.cargo/git
 ENV RUSTC_WRAPPER=cachepot