Auto-open inline entity forms (especially for cardinality: 1)

Especially for a cardinality of "1" (single referenced entity) this would be a HUGE UX benefit!

I'm not sure if this also makes the same sense for multi-value references, but for single values it definitely saves one click and a better workflow!

Here's an example of the current results with the advanced widget referencing a single block_content. You see, why it's not the best you can imagine being forced to always do the Edit ("Bearbeiten") extra click:

The patch is a good first step, but I think the edit form should then also contain the option to remove the entity.

@filsterjisah thanks, yes, I didn't mean to criticize anything. In the opposite, agreed with your idea and added some further points and arguments.

I guess best would be to first have maintainer feedback before proceeding with the implementation. This has UX implications which should be signed off first, I think.

Thanks @Anybody for doing some issue gardening, i really appreciate that.
Working this through...

The feature sounds reasonable, tentative green light for that.

The new function prepareFormState in this issue looks overly complex, but this can be mitigatzed. I'm also open to suck the other issue in here.

So this might mean:
- Move logic from prepareFormState to the place used in the other issue's patch
- Close the other issue as dup of this one
- Add in the feature of the other issue (i don't think we need a setting for that) (and find better query parameter names)
- Manually test
- Add automatic tests

What u think?

git apply inline_entity_form-auto_open_edit_mode-3247446-3.patch 
error: patch failed: config/schema/inline_entity_form.schema.yml:72
error: config/schema/inline_entity_form.schema.yml: patch does not apply
error: patch failed: src/Plugin/Field/FieldWidget/InlineEntityFormComplex.php:105
error: src/Plugin/Field/FieldWidget/InlineEntityFormComplex.php: patch does not apply

I will work on the patch re-roll

Patch re-rolled against 2.0.x branch. Please review

Bulk reopen.

As the issue tag states, this needs tests to be committed.

The approach proposed here does not handle well the situation of nested IEFs, when Cancel is pressed on the parent IEF. This is because of inline_entity_form_close_all_forms() I think, that function seems to override what this patch does.

@jonathanshaw
I don't grok it fully but maybe you can describe the exact steps that uncover the problem you describe, the chances that your objection gets into the tests drastically increase.

Re #20 from memory:
1. Sitebuilder: Nest once complex IEF inside another
2. Sitebuilder: Set the inner one to auto open
3. User: Open an entity in the outer IEF; SUCCESS the inner IEF auto opens properly.
4. User: Cancel the opened outer IEF
5. User Open the same entity again in the outer IEF; FAILURE the inner IEF does not auto open now!

I closed #2792971: Expand inline entity form widget setting as a duplicate. I'm granting credit to @vyasamit2007 and @rhovland for work done on a patch in that issue. But the patch was fairly similar. I don't know that there's anything that would be useful from it.

Everyone please remember to check for existing issues before opening a new one. Today I've closed two issues that were older than this one.