1. A system, comprising: a resource manager executing at one or more computing devices associated with a virtualized computing service of a provider network; and a plurality of virtualization hosts of the virtualized computing service, including a first virtualization host comprising a first field programmable gate array (FPGA); wherein the resource manager is configured to: indicate, to a client of the virtualized computing service via one or more programmatic interfaces, a plurality of categories of compute instances which can be instantiated on behalf of the client, wherein the plurality of categories include at least (a) a first FPGA-enabled category and (b) a second compute instance category which does not support access to an FPGA; identify a particular FPGA-utilizing application to be implemented on behalf of the client at least in part at a compute instance of the first FPGA-enabled category; select, from among the plurality of virtualization hosts, based at least in part on the particular FPGA-utilizing application, the first virtualization host as a platform at which a particular compute instance is to be instantiated on behalf of the client; initiate one or more configuration operations to prepare the first virtualization host for the particular FPGA-utilizing application, wherein a configuration operation of the one or more configuration operations comprises copying, to the first virtualization host, a particular virtual machine image which includes an FPGA library module corresponding to the particular FPGA-utilizing application; and provide an indication, to the client via the one or more programmatic interfaces, of a particular compute instance of the first FPGA-enabled category launched at the first virtualization host using the particular virtual machine image.