1.29.1_arenadata6

Backup privilege statements as separate entries (#31)

Before patch, all privilege statements placed in metadata file as one pre-data
section entry. `editStatementsRedirectSchema()`, used by schema redirection,
replace only first schema name occurrence in entry. This caused a bug - only
first privilege statement was modifed. This, in turn, caused vaious errors.
`gprestore`, used on same database, applied most of privilege statements to
original schema. Or, when used on different database, caused `schema does not
exist` error.

From now, `GetPrivilegesStatements()` returns a set of separate statements,
which later used as separate entries. `strings.TrimSpace()` was removed as all
statements are already trimmed.

Existed tests were modified as separate entries have different format. New test
shows correct privilege applying.