Interface for checking current compiler version in rules

### Prerequisites

- [X] This improvement has not already been suggested.
- [X] This improvement would be generally useful, not specific to my code or setup.

### Engine area

Rules API

### Improvement description

Provide a way to check what the configured Delphi compiler version is from the perspective of a descendant of `DelphiCheck`.
I'd imagine this would become part of the interface for `DelphiCheckContext`.

### Rationale

Currently (as far as I can tell) there is no way for a rule to check what the configured Delphi compiler version is.

Several kinds of rules would benefit from this knowledge, including
* rules that are suggesting use of new language features (e.g. `DigitGrouping`)
* rules that are checking for bugs that only apply to a specific Delphi version (e.g. known unpatched RTL issues)