libobs,libobs-d3d11,libobs-metal,libobs-metal: Rename gs_begin_frame to gs_reset_duplicators

[wanhongqing123]

Description

Rename gs_begin_frame to gs_reset_duplicators

Motivation and Context

gs_begin_frame is only used for windows dxgi screen capture with duplicator, and gs_begin_frame does not have a corresponding gs_end_frame definition.

How Has This Been Tested?

I have tested it in my computor.

Types of changes

• Code cleanup (non-breaking change which makes code smaller or more readable)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[notr1ch]

I don't think what it does is important, if we ever add more features that require work at the beginning of a frame there needs to be a place to put them.

[wanhongqing123]

I don't think what it does is important, if we ever add more features that require work at the beginning of a frame there needs to be a place to put them.

If we need a gs_begin_frame, gs_begin_frame does not have a corresponding gs_end_frame definition. please use gs_begin_scene、 gs_set_render_target、gs_load_swapchain.

[tytan652]

This PR can't be a cleanup one since has it API/ABI breaking changes.