We can omit the "distinct" from some queries
because constraints in the DB ensure uniqueness:

* Groups sub-query
PackageGroup: Primary key makes "PackageID" + "GroupID" unique
Groups: Unique index on "Name" column
-> Technically we can't have a package with the same group-name twice

* Licenses sub-query:
PackageLicense -> Primary key makes "PackageID" + "LicenseID" unique
Licenses -> Unique index on "Name" column
-> Technically we can't have a package with the same license-name twice

* Keywords sub-query:
PackageKeywords -> Primary key makes "PackageBaseID" + "KeywordID" unique
(And a Package can only have one PackageBase)
Keywords -> Unique index on "Name" column
-> Technically we can't have a package with the same Keyword twice

* Packages main-query:
We join PackageBases and Users on their primary key columns
(which are guaranteed to be unique)
-> There is no way we could end up with more than one record for a Package

Signed-off-by: moson-mo <mo-son@mailbox.org>