Fix: pass in the repo root for the 'dir' argument

[jgautier-dd]

In tools that run bazel commands from within bazel run the BUILD_WORKSPACE_DIRECTORY will be set and then in this code the directory will eventually be set to the top level repo root. An example of a tool that this can happen to is the gopackagesdriver in rules_go.

This results in error messages like:

 no such package '@@rules_buf++buf+buf_deps//buf/validate': failed with code: 1, error: gazelle: .: not a subdirectory of repo root

By passing in additional argument it explicitly sets the dir to the directory of the repo. Gazelle itself does something similar

[CLAassistant]

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