Clean up hook implementations in the Taxonomy module

Problem/Motivation

Hooks should be updated to match grouping standards in [meta] Standardize and clean up hook classes in core.

Steps to reproduce

n/a

Proposed resolution

Split out the TaxonomyHooks class, making theme and help new single hook classes, and entity actions a new grouped hook class.

Remaining tasks

Address feedback on MR
Manually convert: taxonomy_theme_suggestions_taxonomy_term, I'd probably put it in with the theme hook

Determine whether to set $config in the constructor or a helper function in TaxonomyEntityHooks.php.
Deprecate taxonomy_build_node_index() and taxonomy_delete_node_index().

User interface changes

None

Introduced terminology

None

API changes

None

Data model changes

None

Release notes snippet

None