Update layers to use new multilinestring functionality

[rustprooflabs]

Tested fix in https://github.com/openstreetmap/osm2pgsql/issues/1386 for #2. It's working!

The D.C. test file with commit 117802c1db2c8e2daab7ca2fdecc47baf3adadc2 returns multilinestrings!

SELECT ST_NumGeometries(geom), COUNT(*)
    FROM osm.road_line
    GROUP BY 1
    ORDER BY 1
;
┌──────────────────┬───────┐
│ st_numgeometries │ count │
╞══════════════════╪═══════╡
│                1 │ 34635 │
│                2 │     1 │
│                3 │     1 │
│                4 │     1 │
│                6 │     3 │
│               10 │     1 │
│               12 │     1 │
│               15 │     1 │
│               32 │     1 │
└──────────────────┴───────┘

[rustprooflabs]

Added multilinestring handling to:

• public_transport
• road_major

Add relation processing (multilinestring and multipolygon) to:

• road_line
• water