Enable borrowed methods on distinct types

[Clemente90]

Motivation

• Allow method declarations to be borrowed on distinct wrapper types so distinct wrappers can forward method overloads and preserve dynamic dispatch and UFCS behavior.
• Update the distinct-subclass test to exercise borrowing method directly instead of asserting the compiler rejects it.

Description

• Updated tests/distinct/tborrow_subclass_methods.nim to declare the subclass kind methods as borrowed (.borrow.) for DistinctAnimal, DistinctDog and DistinctDog2 and adjusted several related test values.
• Unwrapped distinct parameter types when checking whether a routine has an object parameter by changing hasObjParam to accept a PContext and repeatedly calling baseOfDistinct so borrowed methods on distinct wrappers are recognized as object methods.
• Ensure borrowed routines that have return types get a proper result symbol by introducing addResult usage and invoking it when constructing borrowed bodies (semBorrow) and related code paths so codegen has a valid result slot.
• Avoid generating method prototypes/dispatchers for borrowed method declarations by skipping semMethodPrototype/dispatcher creation when sfBorrow is present, preventing incorrect dispatcher generation for borrowed methods.
• Minor AST/result-slot fixups when copying/constructing borrowed symbols so prototypes and dispatchers aren't left with nkEmpty result nodes.

Testing

• Built the compiler with bin/nim c --skipUserCfg --skipParentCfg --hints:off -d:release -o:bin/nim compiler/nim.nim (succeeded).
• Built testament with bin/nim cc --opt:speed -o:testament/testament testament/testament.nim (succeeded).
• Ran the distinct test category with ./testament/testament --nim:bin/nim cat distinct --hints:off and all tests in the distinct category passed.

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Codex Task