[clang-format] Option to place names of functions, constructors and destructors on a new line

I would like to place names of functions, constructors and destructors (declarations and inline definitions) on a new line and leave all possible specifiers (such as `explicit`, `constexpr`, attributes and so on) on a separate line before the function name.

Currently it is possible only for function names using `BreakAfterReturnType: All`, but constructors and destructors have no return type.

Input:
```c++
class SomeClass {
public:
constexpr SomeClass() noexcept = default;

constexpr explicit SomeClass(int x);

[[nodiscard]] std::shared_ptr foo();
};
```

Desired output:
```c++
class SomeClass {
public:
constexpr
SomeClass() noexcept = default;

constexpr explicit
SomeClass(int x);

[[nodiscard]] std::shared_ptr //< Formatted by BreakAfterReturnType: All
foo(); //<
};
```

Start by reproducing the issue's C++ input with clang-format and compare it with BreakAfterReturnType: All. Trace the formatting path for function names, then determine how constructors, destructors, declarations, inline definitions, and preceding specifiers should behave. Done means the shown cases produce the desired line breaks without regressing existing function-name formatting.

Written by the indexing model from the issue text.