Created an endpoint selection modal popup for users to save, add improvements on endpoint selection

[downiec]

Description

The endpoints that are saved will populate the drop-down endpoint selection so that users can choose the endpoint to transfer to. Created the variables to save the endpoint list in the session storage the same as other Globus download data is saved.

Fixes # (issue)

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Local Pre-commit Checks
• CI/CD Build

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• If applicable - I have commented my code, particularly in hard-to-understand areas
• If applicable - I have made corresponding changes to the documentation
• If applicable - I have added tests that prove my fix is effective or that my feature works
• If applicable - New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules