BUG: Fix precision loss in DataFrame.combine_first

[angela-tarantula]

• Part of BUG: Series.combine_first loss of precision #60128
• 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/vX.X.X.rst file if fixing a bug or adding a new feature.

This will fix the following class of precision loss:

>>> a = Series([1666880195890293744], dtype="Int64").to_frame()
>>> b = Series([1,2], dtype="Int64").to_frame()
>>> a
                     0
0  1666880195890293744
>>> b
   0
0  1
1  2
>>> a.combine_first(b)
                     0
0  1666880195890293760
1                    2

See my comment here for more information.

[rhshadrach]

lgtm, cc @mroeschke

[mroeschke]

Thanks @angela-tarantula