Rollup merge of #149332 - asukaminato0721:149324, r=GuillaumeGomez

fix rustdoc search says “Consider searching for "null" instead.” #149324

fix rust-lang/rust#149324

Now builds the “generic parameter” correction banner from discrete sentence fragments and appends the “Consider searching …” clause only when query.proposeCorrectionTo is non-null, so the UI no longer renders null as the suggested type.

Adds a PARSED section with two queries: one typo (Result<SomeTraiz>) that still produces a concrete suggestion and one fully unknown type (Result<NoSuchTrait>) that leaves proposeCorrectionTo null.

Author: Zalathar