- rename "fillContent" of Block to "fillRawContent", since it is filling the rawContent (no direct breaking change)
- added EmbedBlock (retreive url + caption)

- this ensures the currect values within the class attributes

- this ensures the correct values within the textblock classes attributes

- set up BaseFileBlock::class for file-related blocks (file, image, file, pdf)
- implement Modifiable within embed and BaseFileBlock
- mark caption as optional paramter in embed and BaseFileBlock with empty string as default
- set up tests for all new blocks (creation and retreival)

Feature/new blocks

enhanced notion exception by detailed response message

Retrieve a single block @johguentner

- rename "BaseBlockEntity" to "BlockEntity" in BlockEndpoint for clearity
- mark createFileBlock method in BaseFileBlock as final
- replace array_push with array[] = [...] for better performance

polish implementations

block creation + all new current blocks (+ tests for creation/fetch)

- replace notion-api-docs link with updated page (Databases)
- add icon, iconType, cover, coverType to Database and Page with according extraction of different cover- and icon-types
- add database-notion-url retrieval to database
- add raw-information-retrieval to database-retrieval (add as empty properties with according information to property-key and options)
- add retrieval of available options to MultiSelect and Select during database retrieval
- don't retrieve rollup and formula if type-value is not given
- don't retrieve created_time and last_edited_time if retrieved content is null
- fix missing id's and wrong options-field (array in array) within response-json-files

…Filter into new namespace & adding valid filter operators

- and replace == to ===, != to !== in according places

improve database retrieval and add icon/cover

Feature/more filter types