Destructure assist

• Tuple destructuring (implemented in #9855)
• RecordStruct destructuring
• TupleStruct destructuring
• Improve the implementation https://github.com/rust-lang/rust-analyzer/issues/8673#issuecomment-2547827440

It would be nice to have an assist for destructuring a binding into its "subbindings" as in, when you have a name to a tuple value have it destructure into names for each componenet of the tuple, same for structure fields etc. See IntelliJ's implementation here https://github.com/intellij-rust/intellij-rust/blob/master/src/main/kotlin/org/rust/ide/intentions/DestructureIntention.kt

Some examples for how it should work:

let foo$0 = (1, 2, 3);
let bar = foo.0;
let _ = foo.into();

becomes

let (_0, _1, _2) = (1, 2, 3);
let bar = _0;
let _ = (_0, _1, _2).into();

Similarly this should work for TupleStructs and RecordStructs:

struct Foo { bar: i32 }
let foo$0 = Foo { bar: 1 };
let bar = foo.bar;
let _ = foo.into();

becomes

struct Foo { bar: i32 }
let Foo { bar } = Foo { bar: 1 };
let bar = bar;
let _ = (Foo { bar }).into();

This should also respect private fields as well as #[non_exhaustive], putting .. in that case for the fields that aren't exposed.

Start by reviewing the existing destructuring-assist implementation for the already completed tuple, RecordStruct, and TupleStruct cases, then read the linked discussion about improving it. Confirm behavior against the examples, including references to subbindings, private fields, and #[non_exhaustive]; done means the assist handles the requested exposed-field cases without breaking existing behavior.