Support outputting various date styles for postgresql

[MichaelScofield]

What problem does the new feature solve?

Very similar to #3438, currently the GreptimeDB lacks the support for outputting various date styles in pg.

What does the feature do?

Impl the "SET datestyle" for pg client, to print the desired formatted date string for pg users.

Implementation challenges

Same as #3438

[MichaelScofield]

@J0HN50N133 assigned this to you too!

[v0y4g3r]

@J0HN50N133 Please comment on this issue so that I can assign it to you.

[J0HN50N133]

@J0HN50N133 Please comment on this issue so that I can assign it to you.

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