Pre-load fonts so map's local font cache is populated (#334) #274

Job	Run time
FreeBSD (CMake) (LLVM)	11m 36s
macos-11 (CMake) (LLVM)	8m 7s
macos-12 (CMake) (LLVM)	5m 37s
macos-13 (Autotools) (LLVM)	15m 39s
centos:7 (CMake) (GNU)	14m 43s
macos-13 (CMake) (LLVM)	8m 49s
debian:11 (CMake) (GNU)	2m 27s
debian:12 (CMake) (GNU)	2m 39s
debian:testing (CMake) (GNU)	2m 17s
fedora:37 (CMake) (GNU)	3m 44s
fedora:38 (CMake) (GNU)	3m 11s
fedora:rawhide (CMake) (GNU)	3m 32s
ubuntu:20.04 (CMake) (GNU)	2m 44s
ubuntu:22.04 (Autotools) (GNU)	3m 5s
ubuntu:22.04 (Autotools) (LLVM)	2m 26s
ubuntu:22.04 (CMake) (GNU)	2m 32s
ubuntu:22.04 (CMake) (LLVM)	2m 11s
debian:12 (CMake) (GNU) (Latest Mapnik)	25m 44s
ubuntu:22.04 (CMake) (GNU) (Latest Mapnik)	18m 26s
	2h 19m 29s

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