Nextion colors parameters (esphome#5699)

* Add `foreground` color

- Adds `set_component_foreground_color` and `set_component_pressed_foreground_color` which does the same as `set_component_font_color` and `set_component_pressed_font_color` but with a more intuitive name, as this can be used for any component and not only the ones with a text (font).
- I've also reviewed some docstring when related to colors.

* Add numeric color to drawing methods

Should I've used uint32_t instead? In order to keep consistency?

* component color support to uint6_t

This is the right format and is now consistent with colors on drawings.
I'm keeping uint32_t also to avoid breaking changes.

* Enforces uint16_t for colors

uint32_t is incorrect for Nextion display colors.

* Fix clang-format