add --project and --entry flags

[jake-stewart]

removes need for creating temporary knip.json

[webpro]

There are default values for those options, Knip looks in package.json, and plugins look in more configuration files. Do you think there something common missing, or is it just for convenience?

In general I'm not after parity between CLI arguments and configuration file options, especially considering monorepos are supported as well (making CLI args cumbersome).

[jake-stewart]

@webpro i would find the flags useful for scriptability. i could install knip globally and use a wrapper script with the args i prefer. i would be able to use it on any project without having to create a temporary knip.json just to define entry point.

also, i would be able to set different entry points interactively to view different graphs. (i sometimes have multiple entry points)