Move out params parsing of the HttpRequest class

[brunoocasali]

This way we would gain more control about when parsing something or not that even could be
a query_params situation or a body situation.

Fixes #265

[brunoocasali]

Before merging this @curquiza, could you please help me find every place that requires the parsing param feature?

[curquiza]

@brunoocasali Thanks a lot for this PR! 🙏

The place where an "option" can be passed and should be transformed from snake_case into camelCase

• index.documents method, to get all the documents
• client.create_index method, to create an index.
• index.update method, to update the index. Currently you can only update the primary key
• index.search method, to apply the search
• index.update_settings method, to update all the settings

Should NOT be applied to

• index.update_documents and index.add_documents
• to all the sub-settings methods, like index.update_synonyms or index.update_displayed_attributes

So the only missing point is the index.update method I guess :)

[curquiza]

Thanks @brunoocasali

bors merge

[meili-bors]

Build succeeded:

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