BUG: merge with left and/or right empty returning mis-ordered columns

[lukemanley]

• closes BUG: Wrong column order after inner merge operation on empty dataframes. #51929
• closes BUG: Inconsistent column order result using Left Merge depending if left dataframe is empty or not #43087
• closes pd.merge for outer with empty dataframe on the left side results in merged dataframe with the key column not being first #9937
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/v2.2.0.rst file if fixing a bug or adding a new feature.

[mroeschke]

Thanks again @lukemanley