Xontrib-prompt-bar

Added new wrappers:
* `{starshipnoesc}` - remove ANSI escape characters (colors)
* `{starshipnoesc_strip}` - remove ANSI escape characters (colors) and strip (remove white spaces in the begin and end)

Fixed the length calculation in case of using emoji.

Tested and added complete Starship support fixes.

Using Starship cross-shell prompt for rendering sections

Manual calling example:
python
First of all create a starship config to return sections in one line
$STARSHIP_CONFIG = '~/.config/starship_right_sections.toml'
$PROMPT_FIELDS['starship'] = lambda: __xonsh__.subproc_captured_stdout(['starship', 'prompt']).replace('\n', ' ').strip()
$XONTRIB_PROMPT_BAR_RIGHT = '{starship}'
xontrib load prompt_bar

Or for more complete support you can use [xontrib-prompt-starship](https://github.com/anki-code/xontrib-prompt-starship):
python
First of all create a starship config to return sections in one line
$XONTRIB_PROMPT_STARSHIP_RIGHT_CONFIG = "~/.config/starship_xonsh_right.toml"
$XONTRIB_PROMPT_STARSHIP_REPLACE_PROMPT = False
xontrib load prompt_starship
$XONTRIB_PROMPT_BAR_RIGHT = '{starship_right}'
xontrib load prompt_bar

Added showing the current screen in `screens` prompt field.

Replaced `prompt_end` from `$` to `` to support spreading the word about xonsh shell ([more](https://github.com/xonsh/xonsh/issues/4152)).

Added `screens` field.

Example:
python
$XONTRIB_PROMPT_BAR_RIGHT = '{screenssection}{env_namesection}{date_time_tz}'
xontrib load prompt_bar

screen -S scr1
Press Ctrl-A and D to leave the window
screen -S scr2
Press Ctrl-A and D to leave the window

Now you see `scr1, scr2` in the right section.

Back to the scr2:
screen -r scr2

Broken release. Sorry.