add Campaigns nav item to user/org header in central place

Created by: sqs

There is already a list of common nav items for namespaces. We can define the campaign nav item there, and then it will be reused for both users and organizations.

Created by: codecov[bot]

Codecov Report

Merging #14194 into main will increase coverage by 0.15%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main   #14194      +/-   ##
==========================================
+ Coverage   51.32%   51.48%   +0.15%     
==========================================
  Files        1523     1514       -9     
  Lines       77699    77131     -568     
  Branches     7140     6839     -301     
==========================================
- Hits        39881    39710     -171     
+ Misses      34233    33836     -397     
  Partials     3585     3585              

Flag	Coverage Δ
#go	51.74% <ø> (-0.01%)
#integration	29.22% <100.00%> (+0.03%)
#storybook	18.32% <0.00%> (-0.11%)
#typescript	50.85% <100.00%> (+0.52%)
#unit	34.04% <0.00%> (+0.10%)

Impacted Files	Coverage Δ
web/src/enterprise/organizations/navitems.ts	100.00% <ø> (ø)
web/src/enterprise/user/navitems.ts	100.00% <ø> (ø)
web/src/user/area/navitems.ts	100.00% <ø> (ø)
web/src/enterprise/namespaces/navitems.ts	100.00% <100.00%> (ø)
web/src/extensions/extension/extension.ts	72.97% <0.00%> (-5.72%)
shared/src/components/Toggle.tsx	57.14% <0.00%> (-4.40%)
shared/src/components/ToggleBig.tsx	57.14% <0.00%> (-4.40%)
.../internal/codeintel/resolvers/graphql/locations.go	81.44% <0.00%> (-4.13%)
web/src/components/ModalContainer.tsx	0.00% <0.00%> (-3.13%)
...b/src/extensions/extension/ExtensionAreaHeader.tsx	0.00% <0.00%> (-2.95%)
... and 25 more