Dev server refactoring, part 1 (mainly IncrementalGraph) (#22010)

* `IncrementalGraph(.client).File` packs its fields in a specific way to
save space, but it makes the struct hard to use and error-prone (e.g.,
untagged unions with tags stored in a separate `flags` struct). This PR
changes `File` to have a human-readable layout, but adds methods to
convert it to and from `File.Packed`, a packed version with the same
space efficiency as before.
* Reduce the need to pass the dev allocator to functions (e.g.,
`deinit`) by storing it as a struct field via the new `DevAllocator`
type. This type has no overhead in release builds, or when
`AllocationScope` is disabled.
* Use owned pointers in `PackedMap`.
* Use `bun.ptr.Shared` for `PackedMap` instead of the old
`bun.ptr.RefPtr`.
* Add `bun.ptr.ScopedOwned`, which is like `bun.ptr.Owned`, but can
store an `AllocationScope`. No overhead in release builds or when
`AllocationScope` is disabled.
* Reduce redundant allocators in `BundleV2`.
* Add owned pointer conversions to `MutableString`.
* Make `AllocationScope` behave like a pointer, so it can be moved
without invalidating allocations. This eliminates the need for
self-references.
* Change memory cost algorithm so it doesn't rely on “dedupe bits”.
These bits used to take advantage of padding but there is now no padding
in `PackedMap`.
* Replace `VoidFieldTypes` with `useAllFields`; this eliminates the need
for `voidFieldTypesDiscardHelper`.

(For internal tracking: fixes STAB-1035, STAB-1036, STAB-1037,
STAB-1038, STAB-1039, STAB-1040, STAB-1041, STAB-1042, STAB-1043,
STAB-1044, STAB-1045)

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>

src/string/MutableString.zig

@@ -241,14 +241,24 @@ pub inline fn lenI(self: *MutableString) i32 {
 }
 
 pub fn toOwnedSlice(self: *MutableString) []u8 {
-    return self.list.toOwnedSlice(self.allocator) catch bun.outOfMemory(); // TODO
+    return bun.handleOom(self.list.toOwnedSlice(self.allocator));
+}
+
+pub fn toDynamicOwned(self: *MutableString) DynamicOwned([]u8) {
+    return .fromRawOwned(self.toOwnedSlice(), self.allocator);
+}
+
+/// `self.allocator` must be `bun.default_allocator`.
+pub fn toDefaultOwned(self: *MutableString) Owned([]u8) {
+    bun.safety.alloc.assertEq(self.allocator, bun.default_allocator);
+    return .fromRawOwned(self.toOwnedSlice());
 }
 
 pub fn slice(self: *MutableString) []u8 {
     return self.list.items;
 }
 
-/// Clear the existing value without freeing the memory or shrinking the capacity.
+/// Take ownership of the existing value without discarding excess capacity.
 pub fn move(self: *MutableString) []u8 {
     const out = self.list.items;
     self.list = .{};
@@ -258,18 +268,14 @@ pub fn move(self: *MutableString) []u8 {
 /// Appends `0` if needed
 pub fn sliceWithSentinel(self: *MutableString) [:0]u8 {
     if (self.list.items.len > 0 and self.list.items[self.list.items.len - 1] != 0) {
-        self.list.append(
-            self.allocator,
-            0,
-        ) catch unreachable;
+        bun.handleOom(self.list.append(self.allocator, 0));
     }
-
     return self.list.items[0 .. self.list.items.len - 1 :0];
 }
 
 pub fn toOwnedSliceLength(self: *MutableString, length: usize) string {
     self.list.items.len = length;
-    return self.list.toOwnedSlice(self.allocator) catch bun.outOfMemory(); // TODO
+    return self.toOwnedSlice();
 }
 
 pub fn containsChar(self: *const MutableString, char: u8) bool {
@@ -463,3 +469,6 @@ const Allocator = std.mem.Allocator;
 const bun = @import("bun");
 const js_lexer = bun.js_lexer;
 const strings = bun.strings;
+
+const DynamicOwned = bun.ptr.DynamicOwned;
+const Owned = bun.ptr.Owned;