Ignore .direnv for bazel builds (#756)

When building with //..., bazel will traverse down .direnv, which
contains symlinks to the main source tree, so everything gets built
twice.

.bazelignore

@@ -1,5 +1,7 @@
 .cache
 .config
+.direnv
+.devenv
 bazel-bin
 bazel-out
 bazel-remote-bin