Fix error with empty workflow svg and error when saving empty workflow

[BartChris]

Fixes #6290
Adresses #6355 (comment)

Additional changes

• Switch to ViewScoped to prevent having old workflows in the session which migh overwrite another workflow
• Deletion of old workflow files when the title of a workflow get changed

[thomaslow]

@BartChris Are you planning to continue working on this? I am working on refactoring all @SessionScoped form classes, which includes the WorkflowForm, see #6456.

[BartChris]

@thomaslow no, please go ahead, i left it open for quite long and do not want to to interfere with your work. I will close.

[thomaslow]

@BartChris Alright. I'll try to include some of your improvements in my refactoring if there is time.

I also came across this problematic "duplicate" action again (while changing @SessionScoped to @ViewScoped) and came up with another approach instead of this flash context thingy. I simply added a new view parameter "duplicate=true" in case an object should be duplicated. Do you think this is an appropriate solution or do you see any downsides to that? An example is here:

kitodo-production/Kitodo/src/main/java/org/kitodo/production/forms/LdapGroupEditView.java

Lines 86 to 122 in f12ff8e

	public void load(int id, Boolean duplicate) {
	if (Objects.nonNull(duplicate) && duplicate) {
	loadAsDuplicate(id);
	} else {
	loadById(id);
	}
	setSaveDisabled(true);
	}
	/**
	* Load an existing ldap group as duplicate such that it can be saved as a new ldap group.
	*
	* @param id the id of the ldap group that should be duplicated
	*/
	private void loadAsDuplicate(int id) {
	try {
	LdapGroup baseLdapGroup = ServiceManager.getLdapGroupService().getById(id);
	this.ldapGroup = ServiceManager.getLdapGroupService().duplicateLdapGroup(baseLdapGroup);
	} catch (DAOException e) {
	Helper.setErrorMessage(ERROR_DUPLICATE, new Object[] {ObjectType.LDAP_GROUP.getTranslationSingular()}, logger, e);
	}
	}
	/**
	* Load an existing ldap group for editing.
	*
	* @param id the id of the ldap group that will be edited
	*/
	private void loadById(int id) {
	try {
	if (!Objects.equals(id, 0)) {
	this.ldapGroup = ServiceManager.getLdapGroupService().getById(id);
	}
	} catch (DAOException e) {
	Helper.setErrorMessage(ERROR_LOADING_ONE, new Object[] {ObjectType.LDAP_GROUP.getTranslationSingular()}, logger, e);
	}
	}

[BartChris]

Sounds good i would say on first take, especially if it simplifies the logic on form setup. I think this check for the flash context is a little bit cumbersome.

[BartChris]

I will maybe keep it as draft, so this does not get lost, but let you do your work uninterrupted.