[enh] Issue 12567 - Modules can't be marked as deprecated

https://issues.dlang.org/show_bug.cgi?id=12567

Points:

1. Compiler checks the deprecation when the module is imported.

  ```d
  deprecated("std.regexp is deprecated. Please use std.regex instead.")
  module std.regexp
  ```
  ```d
  module test;
  import std.regexp;  // This line will report the message
  ```

2. `ModuleDeclaraion` is necessary if you want to make the module deprecated.

3. Deprecating a module does not deprecate its members automatically.

  It's useful if you want to merely rename modules.

  ```d
  deprecated("std.regexp is renamed to std.regex.")
  module std.regexp;
  /* All members are not implicitly marked as deprecated */
  ```
  ```d
  module std.regex;
  /* Exactly same contents with in std.regexp. */
  ```