cmd squash: alias --to for the --into flag

[ilyagr]

I keep typing --to since I'm used to jj move interface. It is also shorter.

Currently, if I type --to, clap unhelpfully suggests whether I
meant --tool.

Checklist

If applicable:

• I have updated CHANGELOG.md
• I have updated the documentation (README.md, docs/, demos/)
• I have updated the config schema (cli/src/config-schema.json)
• I have added tests to cover my changes

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[ilyagr]

CLA signed.

[bnjmnt4n]

LGTM, I've been typing --to a lot as well.

[ilyagr]

Thank you, Benjamin!

Thanks also, @martinvonz, for actually implementing the squashing of move and squash!