feat: seo canonical link support

[Sebastian-Haehnlein]

PR Type

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• CI-related changes
• Documentation content changes
• application / infrastructure changes
• Other... Please describe:

What Is the Current Behavior?

Issue Number: ISREST-932

What Is the New Behavior?

canonical link support

Does this PR Introduce a Breaking Change?

• Yes
• No

[dhhyi]

This seems to be the way to go. 👍

[dhhyi]

@shauke merge when you are ready 😉

[shauke]

There should be consistent canonical links for category pages too.
The current solution creates canonical links like

<link rel="canonical" href="http://localhost:4200/category/Cameras-Camcorders">

for category pages with subcategories
and canonical links like

<link rel="canonical" href="http://localhost:4200/category/Cameras-Camcorders.832?view=grid">

for category pages with product lists (leaf categories).
The ?view=grid parameter should not be part of the canonical link.

[shauke]

It needs to be clarified if canonical links for Mastered Products should be handled in the same way as in the Responsive Starter Store. See:

<isif condition="#ProductBO:isMastered#">
	<issetcanonicallink
		scope="request"
		name="CanonicalLink"
		action="ViewProduct-Start"
		parameters="#ParameterList(Parameter('SKU', ProductBO:ProductBOMaster:SKU))#">
<iselse>
	<issetcanonicallink
		scope="request"
		name="CanonicalLink"
		action="ViewProduct-Start"
		parameters="#ParameterList(Parameter('SKU', ProductBO:SKU))#">
</isif>

[shauke]

Empty canonical links should probably not be created, e.g. for the /home or /register or /contact pages. Example:

<link rel="canonical">

For content pages like About Us it seems to work well without specific handling.

[fmalcher]

Possibly related: angular/angular#34605