Add stdin input, make every prompt editable

[Shakahs]

This pull request adds support for optionally receiving a prompt from stdin. Also --editor now allows you to edit prompt regardless of prompt source.

Usage:

git diff | sgpt "create a commit message for this diff" 
cat base_prompt.txt | sgpt --editor "additional prompt" 

sgpt will use either stdin prompt or argument prompt, and combine them if both are present. The --stdin-before / -b argument reverses the ordering of the two prompts when combined.

Default ordering:
echo "stdin prompt" | sgpt "argument prompt"

argument prompt
stdin prompt

Reversed ordering:
echo "stdin prompt" | sgpt --stdin-before "argument prompt"

stdin prompt
argument prompt

[lpurdy01]

This is probably fine. After talking to ChatGPT for a bit it looks like it would be more complicated to make it a combo option so in the --help screen it wouldn't show --no-stdin-before

"User:
I'm looking for how do I coude the other side of a bool typed default. Example:

code: bool = typer.Option(False, help="Provide code as output.")

Adds this to the help statment:

│ --code                     --no-code                                              Provide code as output. [default: no-code]                                                                                                     │

Instead of --no-code as the opposite, how would I make that --anti-code
"

"Assistant:
To make the opposite flag --anti-code, you can provide the --code option with customized --anti-code flag using the show_default and opposite parameter of the typer.Option. Here's an example:

import typer

app = typer.Typer()

@app.command()
def main(code: bool = typer.Option(
    False, 
    help="Provide code as output.", 
    show_default="--anti-code", 
)):
    if code:
        typer.echo("Code")
    else:
        typer.echo("Anti-Code")

if __name__ == "__main__":
    app()

In this example, the show_default is set to --anti-code, and while it won't appear as an option in help, the output will show --anti-code as the default opposite flag. To include it as an actual alternative flag, you would need to use two options and process them in your function:

import typer

app = typer.Typer()

@app.command()
def main(
    code: bool = typer.Option(False, "--code", help="Provide code as output."),
    anti_code: bool = typer.Option(False, "--anti-code", help="Provide code as output.")
):
    result = "Neither"
    
    if code and not anti_code:
        result = "Code"
    elif not code and anti_code:
        result = "Anti-Code"
    elif code and anti_code:
        result = "Error: Both --code and --anti-code can't be used simultaneously."

    typer.echo(result)

if __name__ == "__main__":
    app()

Now you explicitly have --code and --anti-code available as options, and the function checks for their combinations and takes appropriate actions accordingly.
"

[lpurdy01]

Looks good to me, and executes fine in codespace.

[TheR1D]

Thank you for the PR, since we are rolling out new versions of sgpt 3-4 times per week, feature branches are getting outdated very fast, this feature was implemented in my branch and merged today #163