Cleanup syntax in bash scripts and create generic platform sdks with ver specific sdks symlinked

[L1ghtmann]

What does this implement/fix? Explain your changes.

• Cleans up the syntax in the shell scripts (never tested their functionality though, so unsure if that was working and still is or not)
• Creates a new AppleTVOS.sdk and iPhoneOS.sdk from the latest sdks of the respective platforms
• Creates two new symlinks (the ver specific sdks that became the generic sdks ^)
• Adds a new script to create these generic sdks and accompanying symlinks

Does this close any currently open issues?

Nope

Any relevant logs, error output, etc?

N/A

Any other comments?

This is meant to be merged if/when 637 logic is introduced to theos. Thought I'd pr since I had this sitting around for a little while and figured it may be helpful for testing.

Where has this been tested?

Operating System: …

Linux (WSL)

Platform: …

Target Platform: …

Toolchain Version: …

SDK Version: …