feat: Introducing StreamingCredentialsProvider for token based authentication (#3320)

* wip

* update documentation

* add streamingcredentialsprovider in options

* fix: put back option in pool creation

* add package level comment

* Initial re authentication implementation

Introduces the StreamingCredentialsProvider as the CredentialsProvider
with the highest priority.

TODO: needs to be tested

* Change function type name

Change CancelProviderFunc to UnsubscribeFunc

* add tests

* fix race in tests

* fix example tests

* wip, hooks refactor

* fix build

* update README.md

* update wordlist

* update README.md

* refactor(auth): early returns in cred listener

* fix(doctest): simulate some delay

* feat(conn): add close hook on conn

* fix(tests): simulate start/stop in mock credentials provider

* fix(auth): don't double close the conn

* docs(README): mark streaming credentials provider as experimental

* fix(auth): streamline auth err proccess

* fix(auth): check err on close conn

* chore(entraid): use the repo under redis org

auth/auth.go

@@ -0,0 +1,61 @@
+// Package auth package provides authentication-related interfaces and types.
+// It also includes a basic implementation of credentials using username and password.
+package auth
+
+// StreamingCredentialsProvider is an interface that defines the methods for a streaming credentials provider.
+// It is used to provide credentials for authentication.
+// The CredentialsListener is used to receive updates when the credentials change.
+type StreamingCredentialsProvider interface {
+	// Subscribe subscribes to the credentials provider for updates.
+	// It returns the current credentials, a cancel function to unsubscribe from the provider,
+	// and an error if any.
+	// TODO(ndyakov): Should we add context to the Subscribe method?
+	Subscribe(listener CredentialsListener) (Credentials, UnsubscribeFunc, error)
+}
+
+// UnsubscribeFunc is a function that is used to cancel the subscription to the credentials provider.
+// It is used to unsubscribe from the provider when the credentials are no longer needed.
+type UnsubscribeFunc func() error
+
+// CredentialsListener is an interface that defines the methods for a credentials listener.
+// It is used to receive updates when the credentials change.
+// The OnNext method is called when the credentials change.
+// The OnError method is called when an error occurs while requesting the credentials.
+type CredentialsListener interface {
+	OnNext(credentials Credentials)
+	OnError(err error)
+}
+
+// Credentials is an interface that defines the methods for credentials.
+// It is used to provide the credentials for authentication.
+type Credentials interface {
+	// BasicAuth returns the username and password for basic authentication.
+	BasicAuth() (username string, password string)
+	// RawCredentials returns the raw credentials as a string.
+	// This can be used to extract the username and password from the raw credentials or
+	// additional information if present in the token.
+	RawCredentials() string
+}
+
+type basicAuth struct {
+	username string
+	password string
+}
+
+// RawCredentials returns the raw credentials as a string.
+func (b *basicAuth) RawCredentials() string {
+	return b.username + ":" + b.password
+}
+
+// BasicAuth returns the username and password for basic authentication.
+func (b *basicAuth) BasicAuth() (username string, password string) {
+	return b.username, b.password
+}
+
+// NewBasicCredentials creates a new Credentials object from the given username and password.
+func NewBasicCredentials(username, password string) Credentials {
+	return &basicAuth{
+		username: username,
+		password: password,
+	}
+}