bug(postgres): cannot parse types from information_schema

[gforsyth]

For the information_schema database, if you attempt to pull a table the types have information_schema. prepended, which breaks our type parsing.

I can't get this to replicate for other databases, so I don't think it's an issue beyond info schema, but still might trip people up.

Additionally, there are several types in Postgres that are only present in information_schema:
https://www.postgresql.org/docs/current/infoschema-datatypes.html

[ins] In [1]: import ibis

[ins] In [2]: con = ibis.postgres.connect(
         ...:     user="postgres",
         ...:     password="postgres",
         ...:     host="0.0.0.0",
         ...:     port=5432,
         ...:     database="ibis_testing",
         ...: )

[ins] In [3]: con.table("domains", database="information_schema")
---------------------------------------------------------------------------
ParseError                                Traceback (most recent call last)
File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/parser.py:1185, in Parser.parse_into(self, expression_types, raw_tokens, sql)
   1184 try:
-> 1185     return self._parse(parser, raw_tokens, sql)
   1186 except ParseError as e:

File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/parser.py:1224, in Parser._parse(self, parse_method, raw_tokens, sql)
   1223 if self._index < len(self._tokens):
-> 1224     self.raise_error("Invalid expression / Unexpected token")
   1226 self.check_errors()

File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/parser.py:1265, in Parser.raise_error(self, message, token)
   1264 if self.error_level == ErrorLevel.IMMEDIATE:
-> 1265     raise error
   1267 self.errors.append(error)

ParseError: Invalid expression / Unexpected token. Line 1, Col: 18.
  information_schema.sql_identifier

The above exception was the direct cause of the following exception:

ParseError                                Traceback (most recent call last)
Cell In[3], line 1
----> 1 con.table("domains", database="information_schema")

File ~/github.com/ibis-project/ibis/ibis/backends/sql/__init__.py:137, in SQLBackend.table(self, name, schema, database)
    134     catalog = table_loc.catalog or None
    135     database = table_loc.db or None
--> 137 table_schema = self.get_schema(name, catalog=catalog, database=database)
    138 return ops.DatabaseTable(
    139     name,
    140     schema=table_schema,
    141     source=self,
    142     namespace=ops.Namespace(catalog=catalog, database=database),
    143 ).to_expr()

File ~/github.com/ibis-project/ibis/ibis/backends/postgres/__init__.py:585, in Backend.get_schema(self, name, catalog, database)
    581 if not rows:
    582     raise com.IbisError(f"Table not found: {name!r}")
    584 return sch.Schema(
--> 585     {
    586         col: type_mapper.from_string(typestr, nullable=nullable)
    587         for col, typestr, nullable in rows
    588     }
    589 )

File ~/github.com/ibis-project/ibis/ibis/backends/postgres/__init__.py:586, in <dictcomp>(.0)
    581 if not rows:
    582     raise com.IbisError(f"Table not found: {name!r}")
    584 return sch.Schema(
    585     {
--> 586         col: type_mapper.from_string(typestr, nullable=nullable)
    587         for col, typestr, nullable in rows
    588     }
    589 )

File ~/github.com/ibis-project/ibis/ibis/backends/sql/datatypes.py:195, in SqlglotType.from_string(cls, text, nullable)
    192 if dtype := cls.unknown_type_strings.get(text.lower()):
    193     return dtype
--> 195 sgtype = sg.parse_one(text, into=sge.DataType, read=cls.dialect)
    196 return cls.to_ibis(sgtype, nullable=nullable)

File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/__init__.py:122, in parse_one(sql, read, dialect, into, **opts)
    119 dialect = Dialect.get_or_raise(read or dialect)
    121 if into:
--> 122     result = dialect.parse_into(into, sql, **opts)
    123 else:
    124     result = dialect.parse(sql, **opts)

File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/dialects/dialect.py:495, in Dialect.parse_into(self, expression_type, sql, **opts)
    492 def parse_into(
    493     self, expression_type: exp.IntoType, sql: str, **opts
    494 ) -> t.List[t.Optional[exp.Expression]]:
--> 495     return self.parser(**opts).parse_into(expression_type, self.tokenize(sql), sql)

File /nix/store/lj17gpqka5s8v7cj3dfqqp4af45wa1pv-python3-3.11.8-env/lib/python3.11/site-packages/sqlglot/parser.py:1190, in Parser.parse_into(self, expression_types, raw_tokens, sql)
   1187         e.errors[0]["into_expression"] = expression_type
   1188         errors.append(e)
-> 1190 raise ParseError(
   1191     f"Failed to parse '{sql or raw_tokens}' into {expression_types}",
   1192     errors=merge_errors(errors),
   1193 ) from errors[-1]

ParseError: Failed to parse 'information_schema.sql_identifier' into <class 'sqlglot.expressions.DataType'>