Refactor Upload_Table to be more readable: split into separate smaller submodules

[radeusgd]

Pull Request Description

• First step of Implement transactional Table Upload / Update / Delete Rows for Snowflake backend #10609 - before I actually modify it, I decided I need to refactor the Upload_Table logic as it was quite convoluted. Doing this as a separate PR for easier review. A big 600+ line file was replaced by several smaller ones grouped by topics.
• Practically no changes apart from moving stuff into separate modules.
• One small change - added Missing_Argument to SQL_Query as I noticed that lack of defaults was giving rise to confusing errors when working with query in the GUI.

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After:

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
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  TypeScript,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• Unit tests have been written where possible.