Swap the eagerly-constructed fontCatalogStore singleton for a lazy
getFontCatalog() accessor (plus __resetFontCatalog for tests), so the
InfiniteQueryObserver is created on first use rather than at module load.
Update the model barrels and all consumers (FontVirtualList, SampleList,
SampleListSection) to the accessor.
Also extract createFontLoadRequestConfig from FontVirtualList: it resolves a
font's URL for a weight and returns a 0-or-1 element array, letting callers
flatMap over a list to build load requests and drop unresolvable fonts in one
pass.
Ilia Mashkov
10603d18bf