Change UpdateUserGroupMembers to accept slice of group members

[painhardcore]

It's really inconvenient api to get members of the group

slack/usergroups.go

Lines 271 to 283 in 1edf0c7

	// GetUserGroupMembersContext will retrieve the current list of users in a group with a custom context
	func (api *Client) GetUserGroupMembersContext(ctx context.Context, userGroup string) ([]string, error) {
	values := url.Values{
	"token": {api.token},
	"usergroup": {userGroup},
	}
	response, err := api.userGroupRequest(ctx, "usergroups.users.list", values)
	if err != nil {
	return []string{}, err
	}
	return response.Users, nil
	}

And then if I need to perform an update - I need to do extra things

slack/usergroups.go

Lines 285 to 302 in 1edf0c7

	// UpdateUserGroupMembers will update the members of an existing user group
	func (api *Client) UpdateUserGroupMembers(userGroup string, members string) (UserGroup, error) {
	return api.UpdateUserGroupMembersContext(context.Background(), userGroup, members)
	}
	// UpdateUserGroupMembersContext will update the members of an existing user group with a custom context
	func (api *Client) UpdateUserGroupMembersContext(ctx context.Context, userGroup string, members string) (UserGroup, error) {
	values := url.Values{
	"token": {api.token},
	"usergroup": {userGroup},
	"users": {members},
	}
	response, err := api.userGroupRequest(ctx, "usergroups.users.update", values)
	if err != nil {
	return UserGroup{}, err
	}
	return response.UserGroup, nil