glib: Add poppler_document_new_from_bytes

This allows creating a PopplerDocument from data stored in a
GBytes.

This is better than poppler_document_new_from_data() since the
document will keep a reference to the data, instead of having
to make sure manually that the data stays around as long as the
document exists. Also poppler_document_new_from_data() is buggy
in that it uses int for the data size instead of gsize.

poppler/poppler#771
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passed #320916
build

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passed #320921
build_android

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passed #320917
build_clang_libcpp

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build_clazy

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build_mingw64_fedora

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passed #320918
build_ubuntu_16_04

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