Support trimming trailing slashes via a mount tuneable to support CMPv2 (#28752)

* Support trimming trailing slashes via a mount tuneable to support CMPv2

* changelog/

* Perform trimming in handleLoginRequest too

* Eagerly fetch the mount entry so we only test this once

* Add a mount match function that gets path and entry

* Update vault/request_handling.go

Co-authored-by: Steven Clark <steven.clark@hashicorp.com>

* more docs

* Some patches (from ENT) didnt apply

* patch fail

* Update vault/router.go

Co-authored-by: Steven Clark <steven.clark@hashicorp.com>

* PR feedback

* dupe

* another dupe

* Add support for enabling trim_request_trailing_slashes on mount creation

* Fix read mount api returning configuration for trim_request_trailing_slashes

* Fix test assertion

* Switch enable and tune arguments to BoolPtrVal to allow end-users to specify false flag

* Add trim-request-trailing-slashes to the auth enable API and CLI

---------

Co-authored-by: Steven Clark <steven.clark@hashicorp.com>

command/secrets_enable_test.go

@@ -120,6 +120,7 @@ func TestSecretsEnableCommand_Run(t *testing.T) {
 			"-allowed-managed-keys", "key1,key2",
 			"-identity-token-key", "default",
 			"-delegated-auth-accessors", "authAcc1,authAcc2",
+			"-trim-request-trailing-slashes=true",
 			"-force-no-cache",
 			"pki",
 		})
@@ -157,6 +158,9 @@ func TestSecretsEnableCommand_Run(t *testing.T) {
 		if exp := true; mountInfo.Config.ForceNoCache != exp {
 			t.Errorf("expected %t to be %t", mountInfo.Config.ForceNoCache, exp)
 		}
+		if !mountInfo.Config.TrimRequestTrailingSlashes {
+			t.Errorf("expected trim_request_trailing_slashes to be enabled")
+		}
 		if diff := deep.Equal([]string{"authorization,authentication", "www-authentication"}, mountInfo.Config.PassthroughRequestHeaders); len(diff) > 0 {
 			t.Errorf("Failed to find expected values in PassthroughRequestHeaders. Difference is: %v", diff)
 		}