refactor use DU insteadof IsCliTool boolean

[enricosada]

for #2938 (repo tool) i need to extend and add a new package type, who is neither a package for references, nor a dotnetcli tool.

But the current codebase store the info if a package is dotnetcli tool as boolean, and that's not really extendible.

Using a boolean make easy to make a mistake in behaviour check, more so if a new type is added. but also in current is may be error prone in checks, for example on filters/etc

this PR convert the IsCliTool: boolean properties to Kind properties of a specific DU

while this PR touch lots of files, is mostly a dumb refactoring:

• false was always a Package type, true was a cliTool
• each DU use a specific type, and conversions are exaustive (no wildcards)