Describe your changes

• Rename GLView to RenderView
• Rename RenderView method: isOpenGLReady to isGfxContextReady
• Rename struct GLContextAttrs to GfxContextAttrs
• Rename RenderView method: setGLContextAttrs to setGfxContextAttrs
• Rename RenderView method: getGLContextAttrs to getGfxContextAttrs
• All renamed stub has compatible typedef like: AX_DEPRECATED(2.8) typedef NewName OldName;

Affects

• User can upgrade from axmol-2.7 without game code changes, but will encouter some deprecated warnings

Issue ticket number and link

Checklist before requesting a review

For each PR

• Add Copyright if it missed:
  - "Copyright (c) 2019-present Axmol Engine contributors (see AUTHORS.md)."

• I have performed a self-review of my code.

  Optional:

  • I have checked readme and add important infos to this PR.
  • I have added/adapted some tests too.

For core/new feature PR

• I have checked readme and add important infos to this PR.
• I have added thorough tests.