Add optional name for RawCSS option

[reboost]

Proposed changes

Added an optional name property to RawCSS option to be used (instead of using undefined) when creating the result's file property.

At the moment the result returns undefined for the file property when using the RawCSS option, adding an identifier name would be great to differentiate between the result of multiple RawCSS data.

Types of changes

What types of changes does your code introduce?

• Bugfix (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 not work as expected)

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

Test for this feature is included.