[schema] improve normalization of RQLExpressions Parse and print back the expression instead of manipulating the string. Among other benefits, it means we don't mangle embedded string constants that contain commas or multiple spaces. Closes #6694426

# re-read ComputedRelation permissions from schema.py now that we're
# able to serialize them
for computedrtype in schema.iter_computed_relations():
    sync_schema_props_perms(computedrtype.type)