Remove RTLD_GLOBAL flag from apps.

[0mdc]

Motivation and Context

This removes the RTLD_GLOBAL flag from python apps, which is no longer required since this magnum update.

The flag is also set in habitat-sim's __init__.py to handle cases where habitat-sim bindings are used before magnum/corrade is imported.

This flag was required before loading native magnum/habitat modules to de-duplicate globals across shared modules. This is now done automatically when importing corrade..

This PR does the same changes in habitat-lab.

How Has This Been Tested

Tested the viewers locally on Linux.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.