api/agent: enable setting SuccessBeforePassing and FailuresBeforeCritical in API (#7949)

Fixes #7764

Until now these two fields could only be set through on-disk agent configuration.
This change adds the fields to the agent API struct definition so that they can
be set using the agent HTTP API.

api/agent.go

@@ -216,6 +216,8 @@ type AgentServiceCheck struct {
 	GRPCUseTLS             bool                `json:",omitempty"`
 	AliasNode              string              `json:",omitempty"`
 	AliasService           string              `json:",omitempty"`
+	SuccessBeforePassing   int                 `json:",omitempty"`
+	FailuresBeforeCritical int                 `json:",omitempty"`
 
 	// In Consul 0.7 and later, checks that are associated with a service
 	// may also contain this optional DeregisterCriticalServiceAfter field,

website/pages/api-docs/agent/check.mdx

@@ -207,6 +207,14 @@ The table below shows this endpoint's support for
 
 - `Status` `(string: "")` - Specifies the initial status of the health check.
 
+- `SuccessBeforePassing` `(int: 0)` - Specifies the number of consecutive successful
+  results required before check status transitions to passing. Available for HTTP,
+  TCP, gRPC, Docker & Monitor checks.
+
+- `FailuresBeforeCritical` `(int: 0)` - Specifies the number of consecutive unsuccessful
+  results required before check status transitions to critical. Available for HTTP,
+  TCP, gRPC, Docker & Monitor checks.
+
 ### Sample Payload
 
 ```json