[lldb] Fix `po` alias by printing fix-its to the console. (#68755)

The `po` alias now matches the behavior of the `expression` command when
the it can apply a Fix-It to an expression.
Modifications

- Add has `m_fixed_expression` to the `CommandObjectDWIMPrint` class a
`protected` member that stores the post Fix-It expression, just like the
`CommandObjectExpression` class.
- Converted messages to present tense.
- Add test cases that confirms a Fix-It for a C++ expression for both
`po` and `expressions`

rdar://115317419