libobs: Code cleanup put swapchain create and swapchain destroy together for easier reading.

[wanhongqing123]

Description

I want to put swapchain create and swapchain destroy together for easier reading

Motivation and Context

I want to put swapchain create and swapchain destroy together for easier reading

How Has This Been Tested?

I have tested in my windows 10 and ubuntu 24

Types of changes

code clean

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.

[Fenrirthviti]

Please properly explain the reason behind these changes. Additionally, this does not meet our commit guidelines, and will need to be more explicit.

[wanhongqing123]

Please properly explain the reason behind these changes. Additionally, this does not meet our commit guidelines, and will need to be more explicit.

I want to put swapchain create and swapchain destroy together for easier reading

[wanhongqing123]

reopen when #12907 is merged.