fix(Path): Fix styles on non-white bg

What does this MR do?

This MR introduces a backgroundColor property to the Path component.

Due to the complex design of the chevron and horizontal scrolling buttons, it was not possible to apply a transparent background and simply inherit styles from a parent element. Therefore, there is a custom backgroundColor property which can be supplied in order to match a parent element's background.

Default	On light gray background with backgroundColor specified	On light gray background without backgroundColor specified

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines.
• GitLab UI's contributing guidlines.
• [-] If it changes a Pajamas-compliant component's look & feel, the MR has been reviewed by a UX designer.
• [-] If it changes GitLab UI's documentation guidelines, the MR has been reviewed by a Technical Writer.
• [-] If the MR changes a component's API, integration MR(s) have been opened in the following projects to ensure that the @gitlab/ui package can be upgraded quickly after the changes are released:
  • [-] GitLab: mr_url
  • [-] Customers Portal: mr_url
  • [-] Status Page: mr_url
• Added the ~"component:*" label(s) if applicable.