Accept numbers with huge exponents; never wrap the exponent

[yuxi-liu-wired]

fix: accept numbers with huge exponents, never wrap the exponent

Two problems with exponents beyond 32 bits in the default (correct)
number parser:

1. Rejected valid input. Once the exponent value passed 2^32 the next
   digit was an InvalidNumber error, so 0e99999999999,
   1e-99999999999 and [2e-44444044280] failed. RFC 8259 §6 puts no
   limit on the exponent; these are zero (serde_json and sonic-rs
   accept them; C++ simdjson saturates the exponent instead of
   failing). Now the exponent saturates and the remaining digits are
   still consumed.

2. Wrong values. The exponent was passed on as exponent as i32, which
   wraps, so exponents just below the cutoff gave wrong finite numbers:

   1e4294967296    1.0      (now: error, out of range like 1e309)
   1e4294967295    0.1      (now: error)
   1e-4294967295   10.0     (now: 0.0)
   1.5e-8589934592 1.5      (now: 0.0)
   

   It now saturates to i32::MIN/MAX, which f64_from_parts already
   maps to 0 or to the out-of-range error.

Test: huge_exponent (fails before this change).

Testing

Each commit adds a regression test that fails before the change. The full test suite passes and
cargo fmt --check is clean on the changed files.

Found with a differential fuzzer comparing serde_json, simd-json, sonic-rs and jiter.