Add Admin Subdomain Middleware

[mikena-truss]

Description

Add the middleware to support the admin subdomain

Reviewer Notes

I feel a little bit like I'm duct taping here. Is there anything we can do to improve this a little while we're in here?

Code Review Verification Steps

• Code follows the guidelines for Logging
• There are no aXe warnings for UI.
• This works in Supported Browsers (Chrome, Firefox, IE, Edge).
• Tested in the Experimental environment (for changes to containers, app startup, or connection to data stores)
• Request review from a member of a different team.
• Have the Pivotal acceptance criteria been met for this change?

References

• Pivotal story for this change

[codecov]

Codecov Report

Merging #1968 into master will decrease coverage by 9.83%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #1968      +/-   ##
=========================================
- Coverage   60.63%   50.8%   -9.84%     
=========================================
  Files         193     446     +253     
  Lines       12288   19434    +7146     
  Branches        0    1695    +1695     
=========================================
+ Hits         7451    9873    +2422     
- Misses       3958    8694    +4736     
+ Partials      879     867      -12

Flag	Coverage Δ
#go	60.44% <100%> (-0.19%)	⬇️
#javascript	34.45% <ø> (?)

Impacted Files	Coverage Δ
pkg/auth/cookie.go	83.21% <100%> (+1.32%)	⬆️
pkg/auth/session.go	59.09% <100%> (+4.09%)	⬆️
pkg/handlers/publicapi/addresses.go	63.33% <0%> (-10.01%)	⬇️
pkg/auth/authentication/auth.go	15.78% <0%> (-5.11%)	⬇️
pkg/services/invoice/fetch_invoice_for_shipment.go	92% <0%> (-2.12%)	⬇️
pkg/models/validators.go	83.33% <0%> (-2%)	⬇️
pkg/models/shipment_line_item.go	68.18% <0%> (-0.94%)	⬇️
pkg/models/user.go	69.69% <0%> (-0.61%)	⬇️
pkg/models/robust_accessorial_line_item.go
pkg/services/paperwork/create_form.go
... and 260 more

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[rdhariwal]

LGTM 🚢 it!

[chrisgilmerproj]

One fix and then this is ready to go.

[chrisgilmerproj]

🤖