Add `trim_scope = "center"`

[Tetrapak0]

When I'm handling a lot of if statements or switch cases, I often find myself either not knowing which function I'm in when dealing with others' codebases (outer), or which if/switch statement I'm in (inner). I'd love to see a feature to remove the context in the center, leaving only the appropriate number of inner and outer context lines, depending on how nested the code is, or how many if/switch statements there are and obviously the value of max_lines.

[topolarity]

I would also love to see this feature, or have it be the default for the 'inner' trim behavior.

To be honest, I feel a bit "lied to" in the inner trim mode, because it strongly suggests I'm in an if-else / switch branch that I actually am not. My preferred behavior would be to have the "prior cases" of if-elses and switches trimmed first, and only resort to pruning scope context afterward (with the direction depending on your inner / outer setting).

As-is, I'm forced to use max_lines: 1 with the inner mode, because I can be reasonably sure it will be a function context that will not have had the most relevant syntax chopped off already.