[JS][BiDi] Add Script module commands and types

[TamsilAmani]

Description

Add script module commands and types

Motivation and Context

Implement script module commands and types as described in https://w3c.github.io/webdriver-bidi/#module-script.
The majority of classes and interfaces are mapping the common data types as described in https://w3c.github.io/webdriver-bidi/#data-types.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[TamsilAmani]

I suggest to add getter functions where ever possible instead of directly accessing the object's attributes. Is that okay?

[TamsilAmani]

Thank you for the review @harsha509. I have pushed the changes.

[harsha509]

LGTM!