Collapsible paper: wrong IDs

[afercia]

See the collapsible papers introduced in #10264.

Passing the HTML output of the Search appearance page through the W3C validator highlights a few occurrences of invalid ID attributes.

Note: I'm testing with WooCommerce activated so I get also the Woo post / taxonomies.

1
empty IDs are invalid: there are 7 occurrences of:
<div class="paper tab-block" id="">

Where the ID is supposed to be the paper ID, which is null by default:
<div class="paper tab-block" id="<?php echo esc_attr( $paper_id ); ?>">

Not sure why the "paper tab-block" needs an ID in the first place, however either we should always pass a paper_id or ensure the ID doesn't get printed out if paper_id is null.

2
IDs can't contain spaces:
The collapsible headings H2 have an ID that is sometimes set to a title passed via a config array or set manually as first parameter passed to WPSEO_Paper_Presenter. See for example admin/views/tabs/metas/archives.php. In one case it's an empty string (general.php). In other cases, it's set to be the post or taxonomy name (to clarify: the $object->labels->name). The passed string may contain spaces and in this case it's an invalid ID. Current occurrences:

<h2 class="help-button-inline" id="Posts">
<h2 class="help-button-inline" id="Pages">
<h2 class="help-button-inline" id="Products">
<h2 class="help-button-inline" id="Categories">
<h2 class="help-button-inline" id="Tags">
<h2 class="help-button-inline" id="Formats">
<h2 class="help-button-inline" id="Product categories">
<h2 class="help-button-inline" id="Product tags">
<h2 class="help-button-inline" id="Product shipping classes">
<h2 class="help-button-inline" id="Author archives settings">
<h2 class="help-button-inline" id="Date archives settings">
<h2 class="help-button-inline" id="Special Pages">

Worth noting setting sections that are not collapsible don't use an ID on the heading. Regardless, I'm not sure what this ID is meant for in the first place.