[Tizen] Re-implemented render external texture gl for impeller to avoid change FlutterOpenGLTexture and use deprecated api

[xiaowei-guan]

We have supported render external texture gl for Impeller
flutter-tizen/engine#368
But this PR has two issues:

1. It modify FlutterOpenGLTexture, it added additional variables, not a good design.

  /// The pixel data buffer.
  const uint8_t* buffer;
  /// The size of pixel buffer.
  size_t buffer_size;
  /// Callback invoked that the gpu surface texture start binding.
  BoolCallback bind_callback;
  /// The type of the texture.
  FlutterGLImpellerTextureType impeller_texture_type;

2. It uses Deprecated API

  // Deprecated: use BlitPass::AddCopy instead.
  [[nodiscard]] bool SetContents(const uint8_t* contents,
                                 size_t length,
                                 size_t slice = 0,
                                 bool is_opaque = false);

So I tried to revert offical PR to render external gl for impeller
flutter/engine#56277
But this PR doesn't work on Tizen platform, I think This PR may not have been verified.
To avoid change FlutterOpenGLTexture and use deprecated api, so I re-implemented render external texture gl for impeller based on this offical PR.
Fix flutter-tizen/embedder#131

[JSUYA]

Sorry for the late review.
I left a comment. Please check it.

[JSUYA]

I'm a little worried because there are a lot of code diffs...

[xiaowei-guan]

I'm a little worried because there are a lot of code diffs...

I think this patch has two advantages:

1. It should improve the performance of rendering textures. I'll share the comparison results later.

2. I'll also try submitting this code to the official repository so that we won't have to merge this part of the code every time in the future.

[JSUYA]

please rebase to 3.38.8 branch