Add slugorcontentbasename and contentbasename

[bep]

• Make it work for all pages, including those created from content adapters and not backed by a file.
• Allow the slug to win, so the new tokens are:

:contentbasename:

1. ContentBaseName

:slugorcontentbasename:

1. Slug
2. ContentBaseName

Note that a page will always have a ContentBaseName, so no need to fall back to e.g. the title.

Closes #11722

[bep]

@jmooring I would appreciate if you could have a quick look at this/take it for a spin. My last take on this makes these new tokens also work with content adapters and pages not backed by any file. I don't see any "catch", but I have said that before and been wrong, so It would be great with a second set of eyes.

[jmooring]

Yeah, this is on my list for today, but there's some life I have to take care of first :)

[jmooring]

This works perfectly. Tested with page kinds:

• page (leaf bundle)
• page (not leaf bundle)
• section (backed by file)
• section (not backed by file)
• term (backed by file)
• term (not backed by file)
• taxonomy (backed by file)
• taxonomy (not backed by file)
• page, section, term, and taxonomy from a content adapter

My only comment: I can't think of a reason for using the :filename or :slugorfilename permalink tokens ever again... so I'm inclined to deprecate them.

If you agree you can place this in config/allconfig/allconfig.go around line 430. I've tested it. Or I can submit a separate PR. Or do nothing.

// Legacy permalink tokens
vs := fmt.Sprintf("%v", c.Permalinks)
if strings.Contains(vs, ":filename") {
	hugo.Deprecate("the \":filename\" permalink token", "Use \":contentbasename\" instead.", "0.144.0")
}
if strings.Contains(vs, ":slugorfilename") {
	hugo.Deprecate("the \":slugorfilename\" permalink token", "Use \":slugorcontentbasename\" instead.", "0.144.0")
}

[bep]

Or I can submit a separate PR. Or do nothing.

Please do that. Doing it as a "separate thing" makes it more visible. If you don't find time, I will put it on my TODO list.

Thanks for the testing of this PR, much appreciated.