Refine spring-boot-starter-data-redis-reactive dependencies

Change `spring-boot-starter-data-redis-reactive` to be standalone and
also declare an explicit dependency on reactor.

Closes gh-37943

spring-boot-project/spring-boot-starters/spring-boot-starter-data-redis-reactive/build.gradle

@@ -5,5 +5,8 @@ plugins {
 description = "Starter for using Redis key-value data store with Spring Data Redis reactive and the Lettuce client"
 
 dependencies {
-	api(project(":spring-boot-project:spring-boot-starters:spring-boot-starter-data-redis"))
+	api(project(":spring-boot-project:spring-boot-starters:spring-boot-starter"))
+	api("io.lettuce:lettuce-core")
+	api("io.projectreactor:reactor-core")
+	api("org.springframework.data:spring-data-redis")
 }

spring-boot-project/spring-boot-starters/spring-boot-starter-data-redis/build.gradle

@@ -6,6 +6,6 @@ description = "Starter for using Redis key-value data store with Spring Data Red
 
 dependencies {
 	api(project(":spring-boot-project:spring-boot-starters:spring-boot-starter"))
-	api("org.springframework.data:spring-data-redis")
 	api("io.lettuce:lettuce-core")
+	api("org.springframework.data:spring-data-redis")
 }