Adding support for backend plugin client middlewares. This allows headers in outgoing
backend plugin and HTTP requests to be modified using client middlewares.
The following client middlewares added:
Forward cookies: Will forward incoming HTTP request Cookies to outgoing plugins.Client
and HTTP requests if the datasource has enabled forwarding of cookies (keepCookies).
Forward OAuth token: Will set OAuth token headers on outgoing plugins.Client and HTTP
requests if the datasource has enabled Forward OAuth Identity (oauthPassThru).
Clear auth headers: Will clear any outgoing HTTP headers that was part of the incoming
HTTP request and used when authenticating to Grafana.
The current suggested way to register client middlewares is to have a separate package,
pluginsintegration, responsible for bootstrap/instantiate the backend plugin client with
middlewares and/or longer term bootstrap/instantiate plugin management.
Fixes#54135
Related to #47734
Related to #57870
Related to #41623
Related to #57065
* plugin client returns error base
* fix api test
* add plugin client test
* add fallback err
* fix linting
* wip
* replace bad query
* template is an error
* failing test of templated error
* add one test passing
* fix failing test
* move test
* rename ErrBadQuery to ErrQueryValidationFailure
* tidy diff
* Change to one error per specific error kind
* last err + fix test
* fix imports
* more tests
* keep req vars together
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
* split out plugin manager
* remove whitespace
* fix tests
* split up tests
* updating naming conventions
* simplify manager
* tidy
* add more fakes
* testing time
* add query verif to int test
* renaming
* add process tests
* tidy up manager tests
* add extra case to int test
* add more coverage to store and process tests
* remove comment
* fix capatilization
* init on provide
* remove addfromsource from API
