[Issue 24654] New: Parameters in contracts should be `const`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24654

          Issue ID: 24654
           Summary: Parameters in contracts should be `const`
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: qs.il.paperinik at gmail.com

Similar to Issue 24565 (out contract variable is implicitly const), function
parameters should only be available as `const` and `scope` in contracts.

At least for `@safe` code.

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