initialValue block setting doesn't work

[wesleybl]

Describe the bug initialValue block setting doesn't work.

To Reproduce Steps to reproduce the behavior:

1. Create a block with the initialValue setting. For example:

   
   function initialValue({ id, value, formData, intl }) {
   return {
   ...formData.blocks[id],
   myField: 'test',
   };
   }
   const applyConfig = (config) => {
   config.blocks.blocksConfig.myBlock = {
   id: 'myBlock',
   initialValue: initialValue,
   ...
   };
   return config;
   };

2. Add the block to a page
3. The `myField` field is not filled with the value 'test'.

**Expected behavior**
The myField field should be filled with the value 'test'.

**Software (please complete the following information):**

Volto 18.0.0-alpha.27
Plone 6.0.10
plone.restapi 9.5.0

**Additional context**
The configuration does not work because the block id that is passed to the `_applyBlockInitialValue` function is the id of the previous block, and not the id of the newly created block. See:

https://github.com/plone/volto/blob/0edcd8083afee783a6463a14b18d0f712cf7c25b/packages/volto/src/helpers/Blocks/Blocks.js#L307

The id passed there should be `newBlockId` and not `id`.

Even making this fix, one thing that still happens is that when the previous one is a block of text, the setting is not applied. The [insertBlock](https://github.com/plone/volto/blob/0edcd8083afee783a6463a14b18d0f712cf7c25b/packages/volto/src/helpers/Blocks/Blocks.js#L288) method is not called in this situation. I wouldn't know where to call `_applyBlockInitialValue` in this situation. I know that the [changeBlock](https://github.com/plone/volto/blob/0edcd8083afee783a6463a14b18d0f712cf7c25b/packages/volto/src/helpers/Blocks/Blocks.js#L341) method is called in this situation. But I don't know if it would be the right place, since it is called several times.

[wesleybl]

@tiberiuichim any tips on how to make this work if the previous block is a text block?

[wesleybl]

In fact, insertBlock is not called if the previous block is an empty text block. If the text block is not empty, insertBlock is called. The difference between adding a block after any block and after a empty text block is here:

https://github.com/plone/volto/blob/24d94848dd60cb051e7a2945c26cc9c2bbb3eef8/packages/volto/src/components/manage/Blocks/Block/EditBlockWrapper.jsx#L109-L115

When the previous block is an empty text block, if returns false and then onChangeBlock is called. In other situations onSelectBlock is called.

Maybe _applyBlockInitialValue has to be called before calling onChangeBlock.

[tiberiuichim]

The id passed there should be newBlockId and not id.

You are correct here