GLES3: Mark CLIP_IGNORE command while batching

[HolySkyMin]

Fixes #74115

EDITED: This PR marks CLIP_IGNORE command while batching to prevent unintended drawing when a canvas item's drawing ends with this command.

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First attempt(was not a good approach):

This PR allows TYPE_CLIP_IGNORE(only when it is saying false and actually changes clipping state) being into GLES3 canvas item batch array. In theory, TYPE_CLIP_IGNORE batch should do nothing, only updating clipping information inside _render_items().

The reason of not adding it when it is saying true is that it changes next batch's clipping data which updates clipping information inside _render_items(). So it is meaningless to add true state into batch array.

[clayjohn]

I'm not sure that this solution will always work. I think right now it appears to work because in the editor, the only place the CLIP_IGNORE is used has the following pattern:

RenderingServer::get_singleton()->canvas_item_add_clip_ignore(ci, true);
 // draw something
RenderingServer::get_singleton()->canvas_item_add_clip_ignore(ci, false);

So the clip ignore command is used in the batch with the drawing, and then the clip_ignore command is added at the end of the drawing and never gets properly unset (because a draw command isn't added after it).

The problem with adding a dummy instance like you do here is that if a draw call is added after this, then its going to draw an extra instance with bogus info.

[HolySkyMin]

Draw call is being added after it in ItemList and RichTextLabel(if I'm not misreading the code), and when I tested them I couldn't find any behaviors malfunctioning.

As I said in initial post, clip ignore command in render phase (after finished batching) should do nothing(only setting up the clip). 'Doing nothing' includes not polluting other draw calls after it. I think it is doing nothing currently, but if it is found out to do something, then we should find another way.

EDIT: I know this is hacky and less intelligent solution. I will find a better way - until then I want to leave this available as an option.

[HolySkyMin]

Found a better solution. Instead of adding batch, just marking CLIP_IGNORE command while batching will have the same result.

[clayjohn]

This will create a batch that does nothing but set the CLIP_IGNORE. However, the actually batching logic will still run. So there should be an early out from the batching loop that exists after updating the clip otherwise it will run the logic to bind the shader, set blend mode, bind texture, etc.

[HolySkyMin]

Added early out while rendering batches. Now a batch with clip ignore command will be skipped immediately.

[clayjohn]

This should happen after clipping is applied, no? With this change, clipping would never get applied.

[HolySkyMin]

CLIP_IGNORE command can't be recorded to the batch as far as I know(instance count remains zero and new batch will not be created in next command), except no other commands are following. So if it is alive in the batch, it's completely useless and can be trashed immediately I think.

[clayjohn]

Superseded by #85778