[clang] [clang] Fix-it hint for `++this` -> `++*this` when deref is modifiable (PR #94159)

[Rajveer Singh Bharadwaj via cfe-commits]

Rajveer100 wrote:

Tests which fail currently:

Clang :: Sema/exprs.c
Clang :: Sema/va_arg_x86_32.c
Clang :: SemaObjCXX/sel-address.mm

Also, what do you think about the fix-it hint wording for errors such as `assignment to cast is illegal, lvalue casts are not supported`?

https://github.com/llvm/llvm-project/pull/94159