feat(ssg): add redirect plugin (#4599)

* feat(ssg): add redirect plugin

* test(ssg): add check for robots noindex meta tag in redirect HTML

* test(ssg): add check for body element in redirect HTML

* style: apply curly rule

* refactor(ssg): use html helper

* docs(ssg): add note about plugin ordering

* fix(ssg): use a single location parameter in redirect HTML generation

* refactor(ssg): move default plugin definition to plugins

* test(ssg): separate built-in plugin tests

* refactor(ssg): convert default plugin to function

* docs(ssg): standardize TSDoc format

* docs(ssg): add usage examples to redirect plugin

* refactor(ssg): rename variable to avoid collision

* fix(ssg): export default plugin

* fix(ssg): support 303, 307, 308 as redirect triggers

* test(ssg): consolidate redirect plugin tests and clarify HTTP Semantics