add factory bot, faker and pull out add attendees method

[kameronk92]

kk Wrote Tests kk Implemented jl Reviewed

Neccesary checkmarks:

[x] All Tests are Passing

[x] The code will run locally

Type of change

[x] New feature
[] Bug Fix

Implements/Fixes:

Broke out the add attendees method to class 'viewing_parties from the controller

Check the correct boxes

[x] This broke nothing
[x] This broke some stuff
[x] This broke everything

Testing Changes

[x] No Tests have been changed
[] Some Tests have been changed
[] All of the Tests have been changed(Please describe what in the world happened)

Checklist:

[x] My code has no unused/commented out code
[x] I have reviewed my code
[x] I have commented my code, particularly in hard-to-understand areas
[x] I have fully tested my code

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