oqapi(attribute-completeness): Allow definition of custom attributes

[mcauer]

• the params attributes and attributeFilter are mutually exclusive

User flow: Alongside usual selection of attributes, offer to the advanced user a dialogue to view already selected attributes as ohsome filter and give him the possibility to edit the filter.

• we need an additional attributeFilterTitle param for the Permalink
• take over already defined named attributes when starting to edit a custom filter
• send query to ohsomeAPI to validate filter string #59
• after completion of dialogue, the previous selection of attributes is replaced by the custom filter
• cancellation of advanced dialogue is possible and previously selected attributes are preserved
• during advanced dialogue a name/title of the attribute represented by the custom filter can be given
• use Prism-code-editor for input field of custom attributeFilter