Populated CSP related directives

- Added TODO
- Copied directives from .htaccess to the ContentSecurityPolicy.php config file.
- Left CSPEnabled set to false in App.php because there is currently no CSP3 support in CI4
- Added `img-src blob:` To Content-Security-Policy header to remove error.

Signed-off-by: objecttothis <objecttothis@gmail.com>
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Internal Server Error - Gitea: Git with a cup of tea
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f