Eliminating whitespace from the parser logic

Hi,

At this time, whitespace tokens are stored in the parser, and are then filtered out in several distinct points in the parser logic, such as:

* https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/parser/mod.rs#L4032-L4049
* https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/parser/mod.rs#L4055-L4069
* https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/parser/mod.rs#L4077-L4094
* https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/parser/mod.rs#L4149-L4160
* https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/parser/mod.rs#L4183-L4202

and many more.

SQL, as far as I know, is not a language that cares about spaces like Python - it should be safe to remove all concepts of whitespaces after [the tokenization process](https://github.com/apache/datafusion-sqlparser-rs/blob/67684c84d4c2589356c411ea4917dcf1defcd77c/src/tokenizer.rs#L937-L942) is complete, and this should:

* Reduce memory requirements, as whitespace tokens would not be stored anymore
* Significantly simplify parser logic by removing all of the whitespace-related logic from the parser
* Move the parser closer to a streaming logic, but that will require many more PRs

Since such a PR would require quite a bit of effort on my part, I would appreciate some feedback on it before moving forward with it.

@iffyio do you happen to have any opinion regarding such a refactoring?

Ciao,
Luca

Commencez par lire la section liée du tokenizer dans src/tokenizer.rs ainsi que les exemples de gestion des espaces blancs dans src/parser/mod.rs. Suivez le parcours des tokens d’espaces blancs, de la tokenisation au filtrage du parser, puis examinez les tests associés du parser s’il y en a. Le travail est terminé lorsque le refactor proposé pour la gestion des espaces blancs est défini de manière cohérente et que le comportement du parser reste couvert.

Rédigé par le modèle d'indexation à partir du texte de l'issue.