Merge bitcoin/bitcoin#23810: docs: avoid C-style casts; use modern C++ casts

7534723 docs: document c-style cast prohibition (Pasta)

Pull request description:

  In the words of practicalswift:
  ```
  A C-style cast is equivalent to try casting in the following order:

      const_cast(...)
      static_cast(...)
      const_cast(static_cast(...))
      reinterpret_cast(...)
      const_cast(reinterpret_cast(...))

  By using static_cast<T>(...) explicitly we avoid the possibility of an unintentional and
  dangerous reinterpret_cast. Furthermore static_cast<T>(...) allows for easier grepping of casts.

  For a more thorough discussion, see "ES.49: If you must use a cast, use a named cast"
  in the C++ Core Guidelines (Stroustrup & Sutter).
  ```

  Modern tooling, specifically `-Wold-style-cast` can enable us to enforce never using C-style casts. I believe this is especially important due to the number of C-style casts the codebase is currently being used as a reinterpret_cast. reinterpret_casts are especially dangerous, and should never be done via C-style casts.

  Update the docs to suggest the use of named cast or functional casts.

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Tree-SHA512: 29a98de396f0c78e32d8a1831319162203c4405a670da5add5da956fcc7df200a1cec162ef1cfac4ddfb02714b66406081d40ed435c7f0f28581cfa24d94fac1

Author: fanquake

doc/developer-notes.md

@@ -109,6 +109,10 @@ code.
   - `++i` is preferred over `i++`.
   - `nullptr` is preferred over `NULL` or `(void*)0`.
   - `static_assert` is preferred over `assert` where possible. Generally; compile-time checking is preferred over run-time checking.
+  - Use a named cast or functional cast, not a C-Style cast. When casting
+    between integer types, use functional casts such as `int(x)` or `int{x}`
+    instead of `(int) x`. When casting between more complex types, use static_cast.
+    Use reinterpret_cast and const_cast as appropriate.
 
 For function calls a namespace should be specified explicitly, unless such functions have been declared within it.
 Otherwise, [argument-dependent lookup](https://en.cppreference.com/w/cpp/language/adl), also known as ADL, could be