Improve interface between compiler and symtable

In this issue I want to try and improve the interface between the compiler and the symtable.

Problems I see are:

• the compiler modifies the symtable
• the compiler performs calculations that the symtable could do (such as in push_inlined_comprehension_state)
• the symtable is actually not a correct representation of some scopes, like those of inlined comprehensions (the comprehension scope it removed from the symtable tree, but is still access from the compiler via the symtable dict). Exception handlers are another example of scope changes that the compiler does, which are not reflected in the symtable.

Linked PRs

• gh-122986

首先阅读 compiler 和 symtable 的实现，重点关注 push_inlined_comprehension_state 以及对 inlined comprehensions 和异常处理器的处理。完成的标准是建立一个更清晰的接口，使 compiler 不修改 symtable，将由 symtable 负责的计算移到其中，并以一致的方式表示作用域变化。