[api] Replace std::vector<uint8_t> with APIBuffer to skip zero-fill (#14593)

esphome/components/api/api_buffer.cpp

@@ -0,0 +1,13 @@
+#include "api_buffer.h"
+
+namespace esphome::api {
+
+void APIBuffer::grow_(size_t n) {
+  auto new_data = make_buffer(n);
+  if (this->size_)
+    std::memcpy(new_data.get(), this->data_.get(), this->size_);
+  this->data_ = std::move(new_data);
+  this->capacity_ = n;
+}
+
+}  // namespace esphome::api