Add as_user flag to jobs fetch

[Dagonite]

Closes #fiaisis/frontend#357

Description

Adds a as_user flag to the jobs endpoint which when true ignores whether the request was made by staff or not.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Project coverage is 85.83%. Comparing base (df51c0c) to head (d13af7f).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
fia_api/router.py	0.00%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #431      +/-   ##
==========================================
+ Coverage   85.15%   85.83%   +0.68%     
==========================================
  Files          28       28              
  Lines         916      925       +9     
==========================================
+ Hits          780      794      +14     
+ Misses        136      131       -5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Pasarus]

Can we add the following tests to ensure execution branches are covered for jobs all:

• As user is on and user, (should be default behaviour)
• As user is off and user, (should be default behaviour)

Can we add the following tests to ensure execution branches are covered for jobs individual instrument:

• As user is on and staff
• As user is on and user, (should be default behaviour)
• As user is off and user, (should be default behaviour)

[Pasarus]

Can we not have commented out tests?