Add more types for function arguments and return values

[syou6162]

resolves https://github.com/datnguye/dbterd/issues/79

Description

As far as I can understand from reading the code, I have assigned types to the arguments and return values of the functions.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (f553725) 100.00% compared to head (51f41f7) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #86 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 31 32 +1 Lines 930 959 +29 ========================================= + Hits 930 959 +29 ```

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