[camera, camera_encoder] Remove stored RAMAllocator member

RAMAllocator is stateless when using default flags — it's just a
dispatch wrapper over heap_caps_malloc/realloc/free. There's no need
to store it as a class member. Use stack-local instances at each call
site instead, matching the pattern used in audio_transfer_buffer and
ring_buffer.

Co-Authored-By: J. Nick Koston <nick@koston.org>

esphome/components/camera/buffer_impl.cpp

@@ -3,18 +3,22 @@
 namespace esphome::camera {
 
 BufferImpl::BufferImpl(size_t size) {
-  this->data_ = this->allocator_.allocate(size);
+  RAMAllocator<uint8_t> allocator;
+  this->data_ = allocator.allocate(size);
   this->size_ = size;
 }
 
 BufferImpl::BufferImpl(CameraImageSpec *spec) {
-  this->data_ = this->allocator_.allocate(spec->bytes_per_image());
+  RAMAllocator<uint8_t> allocator;
+  this->data_ = allocator.allocate(spec->bytes_per_image());
   this->size_ = spec->bytes_per_image();
 }
 
 BufferImpl::~BufferImpl() {
-  if (this->data_ != nullptr)
-    this->allocator_.deallocate(this->data_, this->size_);
+  if (this->data_ != nullptr) {
+    RAMAllocator<uint8_t> allocator;
+    allocator.deallocate(this->data_, this->size_);
+  }
 }
 
 }  // namespace esphome::camera

esphome/components/camera/buffer_impl.h

@@ -18,7 +18,6 @@ class BufferImpl : public Buffer {
   ~BufferImpl() override;
 
  protected:
-  RAMAllocator<uint8_t> allocator_;
   size_t size_{};
   uint8_t *data_{};
 };

esphome/components/camera_encoder/encoder_buffer_impl.cpp

@@ -4,7 +4,8 @@ namespace esphome::camera_encoder {
 
 bool EncoderBufferImpl::set_buffer_size(size_t size) {
   if (size > this->capacity_) {
-    uint8_t *p = this->allocator_.reallocate(this->data_, size);
+    RAMAllocator<uint8_t> allocator;
+    uint8_t *p = allocator.reallocate(this->data_, size);
     if (p == nullptr)
       return false;
 
@@ -16,8 +17,10 @@ bool EncoderBufferImpl::set_buffer_size(size_t size) {
 }
 
 EncoderBufferImpl::~EncoderBufferImpl() {
-  if (this->data_ != nullptr)
-    this->allocator_.deallocate(this->data_, this->capacity_);
+  if (this->data_ != nullptr) {
+    RAMAllocator<uint8_t> allocator;
+    allocator.deallocate(this->data_, this->capacity_);
+  }
 }
 
 }  // namespace esphome::camera_encoder

esphome/components/camera_encoder/encoder_buffer_impl.h

@@ -16,7 +16,6 @@ class EncoderBufferImpl : public camera::EncoderBuffer {
   ~EncoderBufferImpl() override;
 
  protected:
-  RAMAllocator<uint8_t> allocator_;
   size_t capacity_{};
   size_t size_{};
   uint8_t *data_{};