Implement IPA IAM backend (#1005)

feat: FreeIPA IAM implementation

This implements the GetUserAccount() IAM support for accounts stored
within FreeIPA service. This is not implementing any of the account
management functions such as create, update, delete, list IAM accounts,
so is not intended to allow versitygw to manage the IAM accounts within
the FreeIPA service.
---------

Co-authored-by: Yuriy Halytskyy <yuriy.halytskyy@gmail.com>

auth/iam.go

@@ -124,6 +124,12 @@ type Opts struct {
 	CacheDisable           bool
 	CacheTTL               int
 	CachePrune             int
+	IpaHost                string
+	IpaVaultName           string
+	IpaUser                string
+	IpaPassword            string
+	IpaInsecure            bool
+	IpaDebug               bool
 }
 
 func New(o *Opts) (IAMService, error) {
@@ -149,6 +155,9 @@ func New(o *Opts) (IAMService, error) {
 			o.VaultMountPath, o.VaultRootToken, o.VaultRoleId, o.VaultRoleSecret,
 			o.VaultServerCert, o.VaultClientCert, o.VaultClientCertKey)
 		fmt.Printf("initializing Vault IAM with %q\n", o.VaultEndpointURL)
+	case o.IpaHost != "":
+		svc, err = NewIpaIAMService(o.RootAccount, o.IpaHost, o.IpaVaultName, o.IpaUser, o.IpaPassword, o.IpaInsecure, o.IpaDebug)
+		fmt.Printf("initializing IPA IAM with %q\n", o.IpaHost)
 	default:
 		// if no iam options selected, default to the single user mode
 		fmt.Println("No IAM service configured, enabling single account mode")