Support `if` expressions

[cirras]

Prerequisites

• This improvement has not already been suggested.
• This improvement would be generally useful, not specific to my code or setup.

Engine area

Delphi language support

Improvement description

Delphi 13 has introduced a new if conditional operator.

We'll need to:

• parse the new syntax
• handle type resolution by determining the Least Upper Bound (LUB) type from the 2 result expressions
• API: introduce IfExpressionNode node type

Example

Result := if Foo then Bar else Baz;

See

• Conditional Operators (Delphi)

Rationale

Delphi 13 support.