[HttpFoundation] Added missing phpdocs and fixed codestyle

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Added phpdocs for properties and methods that didn't have any or felt short in my opinion, along with some cs fixes like the aligning of assignments etc. 

The idea behind these fixes is that it may increase code readability and can help developers extending these classes to assess the function of each segment of code quicker. It also could help create a more consistent codestyle across the components (primarily using php-cs-fixer).

If appreciated I'd be happy to do the same to the other components, just give me a shout.

**UPDATE**:
- Reverted some of the more redundant or obvious comments that were added. As a sidenote: most comments added are there because their scope is defined as protected, and imo they should therefore explain as much as possible about their usage to ease extending the class by others.