Add support for global and nonlocal symbol renames (#5134)
## Summary
In #5074, we introduced an abstraction to support local symbol renames
("local" here refers to "within a module"). However, that abstraction
didn't support `global` and `nonlocal` symbols. This PR extends it to
those cases.
Broadly, there are considerations.
First, if we're renaming a symbol in a scope in which it is declared
`global` or `nonlocal`. For example, given:
```python
x = 1
def foo():
global x
```
Then when renaming `x` in `foo`, we need to detect that it's `global`
and instead perform the rename starting from the module scope.
Second, when renaming a symbol, we need to determine the scopes in which
it is declared `global` or `nonlocal`. This is effectively the inverse
of the above: when renaming `x` in the module scope, we need to detect
that we should _also_ rename `x` in `foo`.
To support these cases, the renaming algorithm was adjusted as follows:
- When we start a rename in a scope, determine whether the symbol is
declared `global` or `nonlocal` by looking for a `global` or `nonlocal`
binding. If it is, start the rename in the defining scope. (This
requires storing the defining scope on the `nonlocal` binding, which is
new.)
- We then perform the rename in the defining scope.
- We then check whether the symbol was declared as `global` or
`nonlocal` in any scopes, and perform the rename in those scopes too.
(Thankfully, this doesn't need to be done recursively.)
Closes #5092.
## Test Plan
Added some additional snapshot tests.
