Added a method to get all the tile collections

[ronitjadhav]

This Pull Request introduces the following:

• Addition of a new Promise, tileCollections, to the OgcApiEndpoint class in the src/ogc-api/endpoint.ts file. This Promise resolves to an array of tile collection identifiers as strings. It checks if the endpoint offers tiles and if so, it parses the collections to return only those of type 'vector'.
• Update to the parseCollections function in the src/ogc-api/info.ts file. It filters and maps collections based on item type and data type. Now it includes the 'vector' data type in its filtering process, enhancing its ability to parse collections of vector data types.