Only expose velocity relative tp flags to API (#11532)

Since 1.21.2, vanilla split relative teleportation flags into position
and delta/velocity flags into separate enum entries.
This highlighted a design flaw in the paper api addition for teleport
flags, which just simply mirrored internals while also only being able
to apply the delta/velocity part of a flag, given the teleport target is
always absolute in the API.

This patch proposes to simply no longer expose the non-velocity related
flags to the API, instead marking the entire Relative enum as being
purely velocity related, as non-velocity related flags are not useful to
callers. This was done over simply exposing all internal flags, as
another vanilla change to the internal enum would result in the same
breakage.

The newly proposed API *only* promises that the passed flags prevent the
loss of velocity in the specific axis/context, which should be
independent enough of vanillas specific implementation of this feature.

patches/server/1039-API-for-checking-sent-chunks.patch

@@ -5,10 +5,10 @@ Subject: [PATCH] API for checking sent chunks
 
 
 diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-index f071e5cf0bf05e12fb922eb1cd70c7bb4a3cf486..9e4c416ddeccff87ea9ed5b45a2ef04eae2280bf 100644
+index 4fe26b5e492b5cc3ee6b99ec6ade4938acfc9ed8..2c7ec674f55b3178b9dcba7f2bc1ff5efccb50ea 100644
 --- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
 +++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-@@ -3512,6 +3512,35 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+@@ -3510,6 +3510,35 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
      }
      // Paper end