Add llvm-tools to all CCCL devcontainers (#386)

This allows using FileCheck, hopefully from LLVM-18, in all
devcontainers.

This fixes some inconsistency with how FileCheck parses nested `[[[]]]`.

matrix.yml

@@ -43,7 +43,7 @@ x-openmpi: &openmpi { name: "openmpi" }
 x-cccl-dev: &cccl_dev { name: "cccl-dev", hide: true }
 x-clangd-dev: &clangd_dev { name: "llvm", version: "dev", packages: "clangd", hide: true }
 x-clangd-dev-bionic: &clangd_dev_bionic { name: "llvm", version: "19", packages: "clangd", hide: true }
-x-clang-format-cccl: &clang_format_cccl { name: "llvm", version: "18", packages: "clang-format", hide: true }
+x-clang-format-cccl: &clang_format_cccl { name: "llvm", version: "18", packages: "clang-format llvm-tools", hide: true }
 x-clang-format-rapids: &clang_format_rapids { name: "llvm", version: "16", packages: "clang-format", hide: true }
 
 # CCCL only needs a subset of the full CTK: