[tools] improve API docs generation command (#12533)
[tools] improve API docs generation command (#12533)

# Why

Fixes [ENG-869](https://linear.app/expo/issue/ENG-869), [ENG-870](https://linear.app/expo/issue/ENG-870)

Currently there are two minor issues with the `et gdad` command:
* command works only on the workspace root
* modules from packages which include multiple modules cannot be extracted via `-p` flag

# How

This PR fixes the issues mentioned above:
* paths now utilizes the `EXPO_DIR` and `PACKAGES_DIR` constants
* execution with `-p` will now check for the module name also in the definition values 

# Test Plan

* `et gdad` execution was correct from few different subfolders across the workspace
* `et gdad -p expo-pedometer` now generates the JSON file correctly, instead reporting that generation is not supported for the module
exponent/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent