…ture__ handling (pythonGH-98796)This makes a couple related changes to inspect.signature's behaviourwhen parsing a signature from `__text_signature__`.First, `inspect.signature` is documented as only raising ValueError orTypeError. However, in some cases, we could raise RuntimeError.  This PRchanges that, thereby fixingpythonGH-83685.(Note that the new ValueErrors in RewriteSymbolics are caught and thenreraised with a message)Second, `inspect.signature` could randomly drop parameters that itdidn't understand (corresponding to `return None` in the `p` function).This is the core issue inpythonGH-85267. I think this is very surprisingbehaviour and it seems better to fail outright.Third, adding this new failure broke a couple tests. To fix them (and toe.g. allow `inspect.signature(select.epoll.register)` as inpythonGH-85267), Iadd constant folding of a couple binary operations to RewriteSymbolics.(There's some discussion of making signature expression evaluationarbitrary powerful inpythonGH-68155. I think that's out of scope. Theadditional constant folding here is pretty straightforward, useful, andnot much of a slippery slope)Fourth, whilepythonGH-85267 is incorrect about the cause of the issue, it turnsout if you had consecutive newlines in __text_signature__, you'd get`tokenize.TokenError`.Finally, the `if name is invalid:` code path was dead, since`parse_name` never returned `invalid`..(cherry picked from commit79311cb)Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>