User password change (#280)

* start passwordChangeHandler

* add user scope

* add user module / api path

* add password change request

* make comment clearer

* add user to processor

* required true

* add processor call to handler

* don't pass tc or channel

* change password func + tests

* add some first docs about password management

* update swagger docs

* add api tests

* go fmt

* test fixes

internal/api/model/user.go

@@ -0,0 +1,37 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package model
+
+// PasswordChangeRequest models user password change parameters.
+//
+// swagger:parameters userPasswordChange
+type PasswordChangeRequest struct {
+	// User's previous password.
+	//
+	// in: formData
+	// required: true
+	OldPassword string `form:"old_password" json:"old_password" xml:"old_password" validation:"required"`
+	// Desired new password.
+	// If the password does not have high enough entropy, it will be rejected.
+	// See https://github.com/wagslane/go-password-validator
+	//
+	// in: formData
+	// required: true
+	NewPassword string `form:"new_password" json:"new_password" xml:"new_password" validation:"required"`
+}