fix(preamble): Decolor License Fetching + Async Feature

[refcell]

Description

Expose decolored license fetching with blocking calls. This prevents downstream preamble library users from silent coloring, making the call explicitly blocking. Optionally, an async feature should be added that enables colored function calls.

Since preamble's pipeline is executed synchronously, the async feature should not be enabled so that preamble's license fetching is performed synchronously. This should reduce additional tokio runtime overhead.