feat: reduce cognitive complexity (#401)

* refactor: reduce tree traversal complexity

* refactor: -reduce cognitive complexity - extract find-plugins in its own module

* refactor: reduce cognitive complexity of plugin loading algorithm

* fix: annotations idnentation

* refactor, place function in relevant order

* refactor: handlePrefix

* refactor: replaceRouteParamPattern

* refactor: loadPlugins

* refactor: create function to load plugin options

* refactor: rename handlePrefix to handlePrefixConfig

* refactor: findCurrentHooks

* refactor: rename processDir to processDirectory

* refactor: nit

* chore: use strict

* chore: move find-plugin & runtime in lib

* -nrefactor: remove directoryPromises

* refactor: add a buildTree step and improve misleading var identifiers

* refactor: if has no directory, stop the tree construction

Author: jean-michelet