Fix typo initial candidates computation

[ManyTheFish]

When Typo criterion was after a different criterion than Words and the previous criterion wasn't returning any candidates at the first iteration of the bucket sort, then the initial_candidates were lost.

Now, Typoensure to keep the initial_candidates between iterations.

related to meilisearch/meilisearch#3200 (comment)
related to meilisearch/meilisearch#3228

[irevoire]

Nice, from what I understand it works.

I looked at all the other criterion and it look like some (proximity, geo, arc_desc, attribute, exactness) are doing this;

                        match initial_candidates {
                            Some(initial_candidates) => {
                                self.initial_candidates |= initial_candidates
                            }
                            None => self.initial_candidates.map_inplace(|c| c | &candidates),
                        }

While words is doing what you wrote here.
Is there a reason to chose one method over the other?

[Kerollmops]

Looks amazing to me!
bors merge

[ManyTheFish]

@irevoire, Words and Typo criteria contain an Option<InitialCandidates> instead of InitialCandidates, so I had to make a different match.
This comes from the fact that these two criteria are "lazier" than the others because they may not compute any candidates at their step letting the following criterion do it for them.

[ManyTheFish]

Poke @curquiza about this fix.

[bors]

Build succeeded:

• Run Clippy
• Run Rustfmt
• Tests on macos-latest
• Tests on ubuntu-20.04
• Tests on windows-latest

[curquiza]

Is it normal we haven't added any tests here? At least both of the cases reported by the users