Fix FP in default_numeric_fallback when type is context-constrained

[BootstrapperSBL]

fixes #16745

clippy::default_numeric_fallback was flagging numeric literals whose resolved type happened to be i32 / f64, even when that type was forced by a typed neighbor in a binary expression rather than by fallback.

Before

#![warn(clippy::default_numeric_fallback)]
let a = 92i32;
let _ = a + 3;     // warns on `3` even though `a: i32` already pins the type
let b = 92f64;
let _ = b + 3.0;   // warns on `3.0` for the same reason

After

The above no longer warns. The lint now treats a binary operator (other than << / >>) whose sibling operand has a concrete numeric type from a non-(unsuffixed-literal) source as supplying an explicit type bound, the same way it already does for fn arguments and struct fields. The check propagates outer bounds downward, so transitively constrained literals such as the inner ones in a + 1 + 2 and (1 + 2) + a are also accepted.

Shifts are intentionally skipped because << and >> permit each side to have its own integer type, so a typed RHS does not constrain a literal LHS:

let a = 92i32;
let _ = 3 << a;   // still warns: type of `3` is not pinned by `a`

Cases where neither side carries explicit type information continue to warn (e.g. let _ = 1 + 2;).

changelog: [default_numeric_fallback]: do not warn on numeric literals whose type is constrained by a typed operand in a binary expression

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[github-actions]

Lintcheck changes for 9ada8b9

Lint	Added	Removed	Changed
clippy::default_numeric_fallback	0	789	20

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