Update on "[devtool] make ETDumpGen use datasink"

This diff enables customized debug data pipeline by making ETDumpGen leverage user-provided datasink.

Details can be found in https://docs.google.com/document/d/1y_m32mKdj-OgLcLUz9TKhBW3PC3bBDYSBbeAH544EfM/edit?tab=t.0#heading=h.jlkcrurw482r

Differential Revision: [D69647096](https://our.internmc.facebook.com/intern/diff/D69647096/)

[ghstack-poisoned]

Author: Gasoonjia

devtools/etdump/buffer_data_sink.h

@@ -29,7 +29,7 @@ class BufferDataSink : public DataSinkBase {
    * @param[in] buffer A Span object representing the buffer where data will be
    * stored.
    * @param[in] alignment The alignment requirement for the buffer. It must be
-   * a power of two. Default is 64.
+   * a power of two and greater than zero. Default is 64.
    */
   explicit BufferDataSink(
       ::executorch::runtime::Span<uint8_t> buffer,
@@ -42,6 +42,8 @@ class BufferDataSink : public DataSinkBase {
    *
    * @param[in] ptr A pointer to the data blob where data will be stored.
    * @param[in] size The size of the data blob in bytes.
+   * @param[in] alignment The alignment requirement for the buffer. It must be
+   * a power of two and greater than zero. Default is 64.
    */
   BufferDataSink(void* ptr, size_t size, size_t alignment = 64)
       : debug_buffer_((uint8_t*)ptr, size), offset_(0), alignment_(alignment) {}

devtools/etdump/utils.h

@@ -13,7 +13,8 @@ namespace internal {
  * Aligns a pointer to the next multiple of `alignment`.
  *
  * @param[in] ptr Pointer to align.
- * @param[in] alignment Alignment to align to. Must be a power of 2.
+ * @param[in] alignment Alignment to align to. Must be a power of 2 and cannot
+ * be 0.
  *
  * @returns A pointer aligned to `alignment`.
  */