[clang][ExprConstant] Fix display of syntactically-invalid note for member function calls

This patch makes the display of member function calls more true to the user-written code by making use of the syntactical structure of the function calls.
This patch also changes the display of conventional value-based printing from arrow operator to dot operator.
This avoids the syntactical invalidness in notes previously caused by the display of & operator
(lack of parentheses and reference of rvalue)

Fixes https://github.com/llvm/llvm-project/issues/57081

Reviewed By: cjdb
Differential Revision: https://reviews.llvm.org/D151720