refactor(PluginInfo): cleanup & simplify (#132)

* refactor: PluginInfo

* _getTags: simplify

* _getTagsInPlatform: support a list of platforms

* getPodSpecs: remove useless undefined value filtering

* getPodSpecs: further improve formatting

* getPreferences: simplify

* getHookScripts: simplify

* getFrameworks: only determine vars once

* getFrameworks: improve readability

* ctor: improve

* ctor: better var name for root elem

* destructure xml-helpers

* inline addCordova helper

* apply lebab.destruct-params

* convert comments to JSDocs

* remove outdated TODO; sync is faster

* map tags explicitly

* make _getTags* private methods

Co-authored-by: エリス <[email protected]>