Add support for PlanetHowl advertiser network

This update implements support for PlanetHowl as an advertiser network. Key changes include:

Added generatePlanetHowlToken function to handle token generation for PlanetHowl.
Updated the GET and POST methods in networks/route.ts to include PlanetHowl-specific logic and fields.
Modified the NetworkRow component to display the last integration date for PlanetHowl.
Enhanced the AddEditNetworkModal to include input fields for PlanetHowl's Client ID, Client Secret, and Account ID, with links to relevant documentation.
Updated types to include additional fields for advertisers, such as logoUrl and type.

Closes #2

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afftester / affeasy