Grammar: Add LOAD statement to Postgres dialect (#2183)

Co-authored-by: Barry Pollard <barry@tunetheweb.com>

src/sqlfluff/dialects/dialect_postgres.py

@@ -2764,6 +2764,7 @@ class StatementSegment(BaseSegment):
             Ref("DropDatabaseStatementSegment"),
             Ref("AlterFunctionStatementSegment"),
             Ref("AlterViewStatementSegment"),
+            Ref("LoadStatementSegment"),
             Ref("ResetStatementSegment"),
             Ref("DiscardStatementSegment"),
         ],
@@ -3058,6 +3059,20 @@ class DropPolicyStatementSegment(BaseSegment):
     )
 
 
+@postgres_dialect.segment()
+class LoadStatementSegment(BaseSegment):
+    """A `LOAD` statement.
+
+    As Specified in https://www.postgresql.org/docs/14/sql-load.html
+    """
+
+    type = "load_statement"
+    match_grammar = Sequence(
+        "LOAD",
+        Ref("QuotedLiteralSegment"),
+    )
+
+
 @postgres_dialect.segment()
 class ResetStatementSegment(BaseSegment):
     """A `RESET` statement.

test/fixtures/dialects/postgres/postgres_load.sql

@@ -0,0 +1,2 @@
+LOAD 'funzioniGDB.so';
+LOAD '/some/path/funzioniGDB.so';

test/fixtures/dialects/postgres/postgres_load.yml

@@ -0,0 +1,17 @@
+# YML test files are auto-generated from SQL files and should not be edited by
+# hand. To help enforce this, the "hash" field in the file must match a hash
+# computed by SQLFluff when running the tests. Please run
+# `python test/generate_parse_fixture_yml.py`  to generate them after adding or
+# altering SQL files.
+_hash: 552fd1d751752cf3ff213ac044fe72154b22be3497ddf49eef5ac1ef06c1c598
+file:
+- statement:
+    load_statement:
+      keyword: LOAD
+      literal: "'funzioniGDB.so'"
+- statement_terminator: ;
+- statement:
+    load_statement:
+      keyword: LOAD
+      literal: "'/some/path/funzioniGDB.so'"
+- statement_terminator: ;