Tune cargo-watch usage

[laniakea64]

While trying to fix quoting issues in our tests justfile, noticed that our just watch recipe is suboptimal. Not sure about some aspects of fixing it and have some questions:

• --debug is for debugging cargo-watch, and its output overwhelms the actual output we're interested in. Why is this flag being used? Can we remove it?

• run {{FILTER}} is ambiguous when used with our current test suite. How flexible do we want just watch to be? For example, do we want to reuse just watch for the ftdetect tests, with FILTER being --bin=test-ftdetect for that use? or use a separate recipe for watch run ftdetect tests? or have the watch recipe run both syntax & ftdetect tests, passing {{FILTER}} to the syntax tests?

[laniakea64]

--debug is for debugging cargo-watch, and its output overwhelms the actual output we're interested in. Why is this flag being used?

Can't figure this out, even after trying what would've been the current version of cargo-watch at the time this flag was first committed. Wondering if it was unintentionally committed, only added to help confirming the recipe worked as intended?

run {{FILTER}} is ambiguous when used with our current test suite. How flexible do we want just watch to be?

My inclination would be, instead of just watch running cargo directly, have it run just to run other recipes in the tests justfile, specified as recipe parameter. We can use just function error() with conditionals to prevent the recursive just watch watch. Would this be reasonable?