[Impeller] Add OpenGL debugging utilities.

[chinmaygarde]

• CheckFramebufferStatus needs to be called with the enum for the target type and not the target itself.
• Fix dumping the framebuffer type and object name.

The results should be the following for the default FBO0.

[IMPORTANT:flutter/impeller/renderer/backend/gles/render_pass_gles.cc(281)] The default framebuffer (FBO0) was bound.

and the following for an offscreen framebuffer:

[IMPORTANT:flutter/impeller/renderer/backend/gles/render_pass_gles.cc(281)] The default framebuffer (FBO0) was bound.
[IMPORTANT:flutter/impeller/renderer/backend/gles/render_pass_gles.cc(281)] FBO 1: GL_FRAMEBUFFER_COMPLETE
Framebuffer is complete.
Description: 
Color Attachment: GL_TEXTURE(5)
Depth Attachment: GL_RENDERBUFFER(1)
Stencil Attachment: GL_RENDERBUFFER(1)

cc @lyceel

[flutter-dashboard]

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[chinmaygarde]

@lyceel: I added another debugging utility. You can now set log_calls on any proc table entry. So something like:

BindFramebuffer.log_calls = true;
Clear.log_calls = true;

will log all calls to glBindFramebuffer and glClear along with their arguments (decimal encoded).

Only works in IMPELLER_DEBUG.

The following will be dumped to the log:

[IMPORTANT:flutter/impeller/renderer/backend/gles/proc_table_gles.h(118)] glBindFramebuffer(36160, 0)
[IMPORTANT:flutter/impeller/renderer/backend/gles/proc_table_gles.h(118)] glClear(17664)

That should help you trace what Impeller is doing along with the embedder.

[jonahwilliams]

LGTM