Robotframework-browser

New keywords:
- `New Browser`, `New Context` and `New Page` to create playwright objects representing multiple browser instances, browser profiles (contexts) or tabs (pages)
- `Switch Context` and `Switch Page` to switch between open pages
- `Switch Browser` has been added but is unreliable and not recommended for use yet
- `Get Element Count`- gets amount of elements matching `selector` and supports assertion syntax

Other features:
- \>\>\> selector syntax for piercing frames
- Better error messages

New keywords:
- Select Options and Deselect Options (Keywords to manipulate \<select\> element options)
- Wait For Elements State
- Execute Javascript On Page
- Get Page State

The two latter keywords were created to help with frontend JS integration. We will be adding more syntactic sugar and documentation in the near future.

New Features:
- Split keywords between `Type Text` And `Fill Text`. Type text inputs single keypress events (including keyup / keydowns). Fill inputs the text in a single events, like pasting it would.
- `Press Keys` keyword to input series of keypresses (supports Keycodes like ArrowLeft or BackSpace)
- `Clear Text` keyword that clears a textfield
- `Focus` keyword to focus an element
- `Click With Options` keyword to click with different mouse keys and passing other options. See [keyword docs](https://marketsquare.github.io/robotframework-browser/Browser.html) for more details.
- `Add Style Tag` keyword to manipulate page CSS
- `Go Back` and `Go Forward` keywords to use browser's back and forward features
- `Set Timeout` and setting of timeout at library import time. This affects mostly input and getter keywords

- Option to pass `assertion_operator` and `assertion_expected` as parameters to getter keywords to execute assertion
- Deleted older `Text Should Be` style keywords in favor of `Get Text equals content` syntax
- Option to disable headlessness through `headless` argument to keyword `Open Browser` (defaults to false)

- New keywords `Get Element Attribute` (might be renamed later) and `Get Text`.
- New assertion syntax with optional keyword arguments `assertion_operator` and `assertion_value` for `Get _` keywords.

Release adds:
- New keywords for checkboxes, page URLs and screenshots
- Automatic failure screenshots
- Improved CI coverage for our pip package installation