Update SingletonSymNode to allow more comparisons (#108315)
In this PR:
- {in,}equality between singleton and plain ints returns false instead of erroring
- Morally define the semantic of j0 > c to be as if j0 represented an array [s_0, s_1, ... s_n] and s_k > c for all k
- Just like for equality, we don't actually want to do the comparison one by one, instead j0 is constrained to some range [min, max]. By default this range is [2, int64_t::max] so that it acts like a size and passes 0/1 specialization checks.
- In the future, we can define some API to allow users to constrain the range of their singletons
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108315
Approved by: https://github.com/ezyang
