Make package tree shakeable

[flevi29]

Currently there are two sizeable classes exported: MeiliSearch and Index. They contain a lot of methods, whereas the overwhelming majority of websites would only require the search method. We should make these classes tree shakeable, meaning we should split them up into multiple classes.

https://esbuild.github.io/api/#tree-shaking https://web.dev/articles/reduce-javascript-payloads-with-tree-shaking