Exclude reusable blocks from the global block count

[noisysocks]

Fixes #11744.

Modifies getGlobalBlockCount() to exclude reusable blocks from its count. This fixes the block count including reusable blocks that have been parsed and stored into blocks.byClientId but not inserted into the post or page.

How to test

1. Create a new post
2. Insert a block
3. Convert it to a reusable block
4. Click Content Structure
5. It should report that there is 1 block

[jorgefilipecosta]

Hi @noisysocks, this seems an improvement and addresses some problems.
But we need to take into consideration the descendants of the child blocks.
If we convert a columns block with two columns and with one paragraph inside each column to a reusable block, the columns block is not counted but the 2 "column" blocks and 2 paragraph blocks are counted so we have an additional four blocks in the global block count.
We are also taking into account all paragraphs and headings inside reusable blocks in the global headings and paragraphs counts.

[mtias]

We are also taking into account all paragraphs and headings inside reusable blocks in the global headings and paragraphs counts.

I'd consider this a nice to have and not high priority. The most important is to fix the surplus in the counts.

[noisysocks]

Thanks Jorge! Good catch. I've modified the selector to use getClientIdsWithDescendants which does exactly what we need here.

[youknowriad]

Is it really worth memoizing selectors if they depend on these two elements particularly? I feel state.editor.present.blocks.byClientId changes so often that it's just a waste of time to memoize these selectors.

[youknowriad]

Thoughts on this @aduth?

[noisysocks]

But it seems wasteful to have this selector run when something unrelated e.g. a post attribute is modified, no?

[youknowriad]

I don't know honestly, it feels like typing in blocks is the most impactful thing in terms of performance, changing an attribute only get triggered once and not extensively.

Anyway, just something to keep in mind for now, there's no clear "winner"

[youknowriad]

LGTM 👍