Make it easier to target the ipsWidget-class for a pages block

[TSP]

When a block is added in a widget position, it receives an outer li-class as such: 

<li class="ipsWidget ipsWidget_horizontal ipsBox" data-blockid="app_cms_Blocks_52wbf4kut" data-blockconfig="true" data-blocktitle="Egne blokker" data-controller="core.front.widgets.block">
My block html
</li>

I may want to target the ipsWidget-class only for a specific block I've made in Pages because I don't want it to have the padding added for instance. 

I can technically target it as such: .ipsWidget[data-blockid="app_cms_Blocks_52wbf4kut"], but this have some downsides: 

• It's not obvious what I'm targeting (Unless I leave a CSS-comment)
• I can't feel sure the ID wont change
• The ID will be different for each position
• The ID will be different for the same block across different communities

I could also be more general and target .ipsWidget[data-blockid="*app_cms_Blocks"], but I may not want the same rules to apply to all blocks. 

My suggestion is: If a template key is defined for the custom pages block, then incorporate that template-key into the li-element. Some options on how to go about this:

• Add it as a class. For instance class='ipsWidget ipsWidget_horizontal ipsBox custom-block-mykey'
• Add it to data-blockid: data-blockid="app_cms_Blocks_mykey_52wbf4kut"
• Add it to the controller. For example: data-controller="core.front.widgets.block.mykey or data-controller="core.front.widgets.block,core.front.widgets.block.mykey"

[bradl]

I have no idea on the feasibility issues associated but I definitely support the feedback.