v0.29: Add support to matchingPolicy search request parameter

[brunoocasali]

This improvement motivation is about letting the user customize the behavior of Meilisearch when retrieving documents according to the query words.

• Add a matchingStrategy parameter to search requests search and searchRaw.
• The value last is the default strategy if the field is not specified.
• This field can receive only two valid options last or all.

Expected result:

await client.index('movies').search('shifu', matchingStrategy: 'last');

Good to have: Make the last or all constants where we could quickly use them without mistakes.