[0.82] Update `generate-artifacts-executor` script to account for optional output path

[kitten]

Target Branch

0.82

Link to commit or PR to be picked

https://github.com/facebook/react-native/pull/54609

Description

baseOutputPath is an optional input for generate-artifacts-executor but wasn't marked as such, and can also be overridden. This was missed and caused a regression for:

• Resolving the generated autolinking.json file
• Writing a relative path in generateReactCodegenPodspec

Restores:

• react-native codegen being run without an --outputPath argument
• codegen running with a package.json:codegenConfig.outputDir override