feat: import Bazel version specific run commands

Add four new environment variables for run command substitution:

- `BAZEL_MAJOR_VERSION`
- `BAZEL_MAJOR_MINOR_VERSION`
- `BAZEL_MAJOR_MINOR_PATCH_VERSION`
- `BAZEL_VERSION` (same as `BAZEL_MAJOR_MINOR_PATCH_VERSION`)

These can be used to import version specific run commands.

```
try-import %workspace%/.bazelrc.${BAZEL_MAJOR_MINOR_PATCH_VERSION}
try-import %workspace%/.bazelrc.${BAZEL_MAJOR_MINOR_VERSION}
try-import %workspace%/.bazelrc.${BAZEL_MAJOR_VERSION}
```