chore: Add _typing_compat module

[dangotbanned]

What type of PR is this? (check all applicable)

• 💾 Refactor
• ✨ Feature
• 🐛 Bug Fix
• 🔧 Optimization
• 📝 Documentation
• ✅ Test
• 🐳 Other

Related issues

• Mentioned in (perf: Avoid module-level importlib.util.find_spec #2391 (comment))
• Needed again for (feat(RFC): A richer Expr IR #2572)

Checklist

• Code follows style guide (ruff)
• Tests added
• Documented the changes

If you have comments or can explain your changes, please do so below

Module doc preview

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I was originally expecting we'd need to add some config for ruff and mypy.
Haven't had any issues without it, so I'm not sure we need it?

[dangotbanned]

To expand on the link to (#2572) some more ...

Ideally, it would be good to (statically) know the type of every node in an expression.
Pragmatically, it would be good to preserve the static types where we can - but fall back to a base class (default) when we can't.

There's a big benefit to knowing as much information of the graph as possible - to avoid needing assert, isinstance, cast, etc littered everywhere

[MarcoGorelli]

nice, thanks @dangotbanned