Some syntax errors, and a bug in the query method.

[sindrsh]

Bug report

Trying out the 4.x branch with Godot 4, some syntax errors pops up in the editor. Also, variable query_result of ´DatabaseTask´ stays null when performing queries even though data is fetched.

Suggested fixes

After making the following changes, syntax error messages disappears, and log in and query for selection is successful.

SupabaseQuery
83: Replace query_struct[key].empty() with query_struct[key].is_empty()
244: Filters.PHFLTS should be Filters.PHFTS

SupabaseAuth
71: Replace AuthTask.new._setup( with AuthTask.new()._setup
75: Replace payload with JSON.stringify(payload)
BaseTask
34: remove true as an argument of the function.

DataBaseTask
17: Add line above: query_result = result_body
24: Replace data with _data (?)