Fix(snowflake): parse CREATE SEQUENCE with commas

[georgesittas]

Fixes #3435

Note that the two DDLs tested produce slightly different ASTs:

>>> import sqlglot
>>> sqlglot.parse_one("CREATE SEQUENCE seq1 WITH START=1 INCREMENT=1 ORDER", "snowflake")
Create(
  this=Table(
    this=Identifier(this=seq1, quoted=False)),
  kind=SEQUENCE,
  properties=Properties(
    expressions=[
      Property(
        this=Identifier(this=START, quoted=False),
        value=Literal(this=1, is_string=False)),
      Property(
        this=Identifier(this=INCREMENT, quoted=False),
        value=Literal(this=1, is_string=False)),
      SequenceProperties(
        options=[
          Var(this=ORDER)])]))
>>> sqlglot.parse_one("CREATE SEQUENCE seq1 WITH START=1, INCREMENT=1 ORDER", "snowflake")
Create(
  this=Table(
    this=Identifier(this=seq1, quoted=False)),
  kind=SEQUENCE,
  properties=Properties(
    expressions=[
      Property(
        this=Identifier(this=START, quoted=False),
        value=Literal(this=1, is_string=False)),
      SequenceProperties(
        increment=Literal(this=1, is_string=False),
        options=[
          Var(this=ORDER)])]))

This happens because when we only have KEY=VALUE pairs separated by whitespace we don't ever reach _parse_sequence_properties, but when there's a comma we do reach it and so the SequenceProperties is produced. It's not 100% clean but not sure if a refactor is high ROI right now to make the two ASTs match.