Component decorators (#354)

Add decorator variants for decorator components

Add the "pipe" operator for components, similar to what was done for Elements.
We are able to put something like:
```
Button(...) | Maybe(&show_button)
```

Add decorators for:
- `Maybe`
- `CatchEvent`
- `Renderer`

Signed-off-by: Kefu Chai <tchaikov@gmail.com>
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

examples/dom/hflow.cpp

@@ -1,4 +1,3 @@
-#include <stddef.h>                // for size_t
 #include <stdio.h>                 // for getchar
 #include <ftxui/dom/elements.hpp>  // for operator|, size, Element, text, hcenter, Decorator, Fit, WIDTH, hflow, window, EQUAL, GREATER_THAN, HEIGHT, bold, border, dim, LESS_THAN
 #include <ftxui/screen/screen.hpp>  // for Full, Screen

examples/dom/vflow.cpp

@@ -1,4 +1,3 @@
-#include <stddef.h>                // for size_t
 #include <stdio.h>                 // for getchar
 #include <ftxui/dom/elements.hpp>  // for operator|, Element, size, text, hcenter, Fit, vflow, window, EQUAL, bold, border, dim, HEIGHT, WIDTH
 #include <ftxui/screen/screen.hpp>  // for Full, Screen