Fix/setup and template fixes

[twhlynch]

remove unneeded offset of vr camera position
with the -1.8 offset on the vr camera it would be under the map. now it is correctly with ground level at the ground. non vr camera still starts in the ground, as it did previously. id guess the -1.8 thing used to be needed but now its unneeded.

explicitely use python3 in regenerate script for compatability
some systems map python to python2, and some dont have it at all. generally its expected that python3 will exist so it should be used in unix scripts (https://peps.python.org/pep-0394/)

fix issues breaking compiling

• bump std to c++20 which is required for rayne
• enable UI to fix FlexUI not compiling

update xcode signing identity and remove hardcoded id

• "Apple Development" is the current only option for signing certs
• i removed the hardcoded id and just left it with a placeholder. this should be fine as the behaviour of the first build prompting it to be set stays, and someone using the template can hardcode their own id if needed.

refactor CreateProject script
made slightly more readable and added __TMP_BUNDLE_DOMAIN__ which would be like 'com.slindev'

remove hardcoded bundle domain and add to CreateProject script
com.slindev was hardcoded, now it uses the above mentioned __TMP_BUNDLE_DOMAIN__

modernise gitignore
editor configs, lsp output, comments

clean up cmakelists making use of cmake variables

• reduces the amount of __TMP__ variables by using cmakes ${PROJECT_NAME} variable and setting variables at the start like LIBRARY_NAME and BUNDLE_ID
• GRAB was hardcoded in around $<TARGET_FILE_DIR:GRAB> $<TARGET_RUNTIME_DLLS:GRAB>
• merged some set_target_properties for readability
• replaced setting a compile definitions variable per OS with directly calling target_compile_definitions. it seemed to be that way so it could accumulate definitions easier, but target_compile_definitions accumulates by default so that was redundant