filer: add username and keyPrefix support for Redis stores (#7591)

* filer: add username and keyPrefix support for Redis stores

Addresses https://github.com/seaweedfs/seaweedfs/issues/7299

- Add username config option to redis2, redis_cluster2, redis_lua, and
  redis_lua_cluster stores (sentinel stores already had it)
- Add keyPrefix config option to all Redis stores to prefix all keys,
  useful for Envoy Redis Proxy or multi-tenant Redis setups

* refactor: reduce duplication in redis.NewClient creation

Address code review feedback by defining redis.Options once and
conditionally setting TLSConfig instead of duplicating the entire
NewClient call.

* filer.toml: add username and keyPrefix to redis2.tmp example

weed/command/scaffold/filer.toml

@@ -201,8 +201,11 @@ table = "seaweedfs"
 [redis2]
 enabled = false
 address = "localhost:6379"
+username = ""
 password = ""
 database = 0
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -217,6 +220,8 @@ masterName = "master"
 username = ""
 password = ""
 database = 0
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -232,7 +237,10 @@ addresses = [
     "localhost:30005",
     "localhost:30006",
 ]
+username = ""
 password = ""
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -248,8 +256,11 @@ superLargeDirectories = []
 [redis_lua]
 enabled = false
 address = "localhost:6379"
+username = ""
 password = ""
 database = 0
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -264,6 +275,8 @@ masterName = "master"
 username = ""
 password = ""
 database = 0
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -279,7 +292,10 @@ addresses = [
     "localhost:30005",
     "localhost:30006",
 ]
+username = ""
 password = ""
+# prefix for filer redis keys
+keyPrefix = ""
 enable_tls = false
 ca_cert_path = ""
 client_cert_path = ""
@@ -373,8 +389,10 @@ dialTimeOut = 10
 enabled = false
 location = "/tmp/"
 address = "localhost:6379"
+username = ""
 password = ""
 database = 1
+keyPrefix = ""
 
 [tikv]
 enabled = false