Typos and errors in docs

Error in code example

Support for separating Read/Write Database

Improved global configuration of assetmanager

all fine now

closes #2427

Added `beforeCopy`, `afterCopy`, `forceCopy` properties to AssetManager

fixes #4209

Update input-file-upload.md

fix docs

- Removed hacks since these are no longer required: https://github.com/Codeception/Codeception/commit/71db233985531f298264dc4ca0160d2aa1c83b7f
- Removed unused helper classes
- Added 2.0 style "actor" to config

Thanks to @Ragazzo and @DavertMik for helping with it.

`yii\mongodb\Collection::buildRegexCondition()` added.