Make captcha and password optional for external accounts (#6606)

templates/user/auth/signin_inner.tmpl

@@ -15,10 +15,12 @@
 				<label for="user_name">{{.i18n.Tr "home.uname_holder"}}</label>
 				<input id="user_name" name="user_name" value="{{.user_name}}" autofocus required>
 			</div>
+			{{if not .DisablePassword}}
 			<div class="required inline field {{if and (.Err_Password) (or (not .LinkAccountMode) (and .LinkAccountMode .LinkAccountModeSignIn))}}error{{end}}">
 				<label for="password">{{.i18n.Tr "password"}}</label>
 				<input id="password" name="password" type="password" value="{{.password}}" autocomplete="off" required>
 			</div>
+			{{end}}
 			{{if not .LinkAccountMode}}
 			<div class="inline field">
 				<label></label>