PuppetManifest: minor improvements

[masatake]

PuppetManifest parser is the primary testbed for multi-table parsing and optscript.

Items must be solved before merging optscript (#2794)

• [ ] fill typeref fields of type kind objects
• [ ] fill typeref fields of parameters of classes and definitions (See https://puppet.com/docs/puppet/7.6/lang_type_aliases.html)

General items:

• [ ] tag node definitions
• [ ] skip here documents (https://github.com/puppetlabs/puppet-specifications/blob/master/language/heredoc.md)

Solved in optscript branch:

• [x] fill signature fields of classes
• [x] tag parameters of a class
• [x] fill inherits fields of classes
• [x] tag parameters of a definition
• [x] fill signature fields of definitions
• [x] introduce a kind for virtual resources

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~https://puppet.com/docs/puppet/7.6/puppet_language.html~ https://github.com/puppetlabs/puppet-specifications/tree/master/language