Add `saml-configured`, `jwt-configured` and `google-auth-configured` settings, and some general setting refactor

[noahmoss]

This PR contains some refactor of various SSO settings to support FE changes being done by @ranquild in #26040 and #26064. This is a replacement for #25869 which was the wrong approach.

The end state of this PR is: For JWT and SAML, there is both a jwt/saml-configured setting and a jwt/saml-enabled setting. The -configured settings just check that a couple of the required settings are set for each SSO method. The -enabled settings are simple booleans controlled by toggles on the UI, but only returns true if the configured setting is also true, and these are the settings that should be used when determining whether a given SSO method should be allowed for logins. I've also added google-auth-configured which just checks for the presence of the client ID, as a convenience for the frontend.

[codecov[bot]]

Codecov Report

Base: 64.25% // Head: 64.25% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (48e013c) compared to base (d1c6127). Patch coverage: 73.68% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #26045   +/-   ##
=======================================
  Coverage   64.25%   64.25%           
=======================================
  Files        3087     3087           
  Lines       91307    91316    +9     
  Branches    11490    11491    +1     
=======================================
+ Hits        58667    58676    +9     
+ Misses      28028    28027    -1     
- Partials     4612     4613    +1     

Flag	Coverage Δ
back-end	85.55% <77.77%> (+<0.01%)	:arrow_up:
front-end	44.89% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...kend/src/metabase_enterprise/sso/api/interface.clj	62.50% <0.00%> (ø)
...ise/frontend/src/metabase-enterprise/auth/index.js	25.80% <0.00%> (ø)
frontend/src/metabase/lib/settings.ts	47.61% <0.00%> (ø)
.../src/metabase_enterprise/sso/integrations/saml.clj	76.06% <20.00%> (ø)
...d/src/metabase_enterprise/sso/integrations/jwt.clj	93.84% <66.66%> (ø)
...abase_enterprise/sso/integrations/sso_settings.clj	95.29% <95.45%> (+0.35%)	:arrow_up:
src/metabase/integrations/google.clj	94.59% <100.00%> (+0.22%)	:arrow_up:
src/metabase/public_settings.clj	94.55% <100.00%> (ø)
src/metabase/models/query.clj	92.30% <0.00%> (ø)

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