Custom parser can handle nested ICU messages even if they
are split into multiple fragments. Code reworked to encapsulate
all pseudolocalization logic in Pseudolocalizer and PseudoMethods
classes. To minimize a changelist size, some static functions
remained. Fake BiDi pseudolocalization method is reimplemented
to handle word boundaries correctly. Unit tests added.
(cherry picked from commit cbb1e676b56677ae3585c067f29646dddffb4857)
bug: 22060509
Change-Id: I11968d81984d99501a4d9334ff2e7453a1eb7a00
729ffa299c