safekeeper: exclude API (#10757)

## Problem

https://github.com/neondatabase/neon/pull/10241 added configuration
switch endpoint, but it didn't delete timeline if node was excluded.

## Summary of changes

Add separate /exclude API endpoint which similarly accepts membership
configuration where sk is supposed by be excluded. Implementation
deletes the timeline locally.

Some more small related tweaks:
- make mconf switch API PUT instead of POST as it is idempotent;
- return 409 if switch was refused instead of 200 with requested &
current;
- remove unused was_active flag from delete response;
- remove meaningless _force suffix from delete functions names;
- reuse timeline.rs delete_dir function in timelines_global_map instead
of its own copy.

part of https://github.com/neondatabase/neon/issues/9965

libs/safekeeper_api/src/membership.rs

@@ -85,12 +85,12 @@ impl MemberSet {
         Ok(MemberSet { m: members })
     }
 
-    pub fn contains(&self, sk: &SafekeeperId) -> bool {
-        self.m.iter().any(|m| m.id == sk.id)
+    pub fn contains(&self, sk: NodeId) -> bool {
+        self.m.iter().any(|m| m.id == sk)
     }
 
     pub fn add(&mut self, sk: SafekeeperId) -> anyhow::Result<()> {
-        if self.contains(&sk) {
+        if self.contains(sk.id) {
             bail!(format!(
                 "sk {} is already member of the set {}",
                 sk.id, self
@@ -130,6 +130,11 @@ impl Configuration {
             new_members: None,
         }
     }
+
+    /// Is `sk_id` member of the configuration?
+    pub fn contains(&self, sk_id: NodeId) -> bool {
+        self.members.contains(sk_id) || self.new_members.as_ref().is_some_and(|m| m.contains(sk_id))
+    }
 }
 
 impl Display for Configuration {