Add option to specify separator for text output

[mkatychev]

Added --separator <str> flag for taplo get.

From the helpdoc:

 --separator <SEPARATOR>
        A string that separates array values when printing to stdout.

        If `--separator` is specified with a non text output format, the operation will fail.

[ia0]

Thanks for the PR!

Out of curiosity, what's the motivation behind this change? Which separator do you want to use and in which context?

[mkatychev]

Thanks for the PR!

Out of curiosity, what's the motivation behind this change? Which separator do you want to use and in which context?

This would be to pass in the result of taplo get -f rust-toolchain.toml 'toolchain.components' to dtolnay/rust-toolchain, the GHA asks for a comma separated string to install said components

[ia0]

Thanks for the PR and the motivation explanation!