[ios,android] Implement local ideographic glyph generation for MapSnapshotter

[ChrisLoer]

#10522 introduces support for local generation of ideographic glyphs. For maps that use lots of CJK glyphs, this can lead to a dramatic reduction in data usage. The Android and iOS implementations of MapSnapshotter don't currently take advantage of this setting, so for a CJK user using the local override, a map might load with 1MB worth of data, but taking a snapshot of that map might require downloading an extra 10MB of glyph data.

HeadlessFrontend already supports a localFontFamily argument, so the only change to portable code required here is to pass that argument through the MapSnapshotter constructor.

The Android implementation will need to expose an appropriate option to the Java MapSnapshotter class. The iOS implementation may take advantage of the existing MGLIdeographicFontFamily setting in Info.plist.

[ChrisLoer]

/cc @chriswu42 @1ec5 @zugaldia @akitchen @lilykaiser

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[zugaldia]

MapSnapshotter is actively used with maps that use CJK glyphs, I understand this is an improvement we still want to do. Tagging @chloekraw for confirmation and prioritization.

[chriswu42]

@ChrisLoer can you verify that this work is now completed?

[ChrisLoer]

Yup, we just fixed this with #13427, we just forgot about the tracking issue!