fix: keep view templates inside the views directory

[ambrose5773]

Summary

View::getTemplate() now rejects absolute template paths and any path that resolves outside the configured views directory. render(), fetch(), and exists() all go through that resolver, so a template that cannot be shown to stay inside the views directory is not included.

Reported by Arekkusul.

Test plan

• A normal view under the views path still renders
• A path that leaves the views directory is rejected
• An absolute path is rejected
• Full PHPUnit suite: 496 tests, 964 assertions

[enlivenapp]

Howdy folks,

I saw this come across the Discord channel and thought I'd pop over and toss in my 25 cents (inflation, ya know).

This would change getTemplate() from returning full paths to throwing, and would flip a test that checks the old behavior. Anyone on ^3.0 might get blindsided if this is a patch (an assumption since it's fix: in the commit.)

exists() looks like it would throw, which would break if ($view->exists($f)).

A missing views folder and a disallowed path would give the same message, Template path is not allowed.

Pubvana (my cms) overrides flight\template\View::getTemplate() currently so this doesn't really break anything for me as written but if flight\template\View::render() or flight\template\View::fetch() change that'd blow me up since I do call them with absolute paths.

Anyway, figured I'd toss that stuff out for consideration. ☮️