Support ML.PREDICT a.k.a. TVF with path

[apstndb]

https://cloud.google.com/spanner/docs/reference/standard-sql/ml-functions#mlpredict

ML.PREDICT(input_model, input_relation[, model_parameters])

input_model:
  MODEL model_name

input_relation:
  { input_table | input_subquery }

input_table:
  TABLE table_name

model_parameters:
  STRUCT(parameter_value AS parameter_name[, ...])

I think it can be a generalized as TVF with path name.

ZetaSQL references

https://github.com/google/zetasql/blob/194cd32b5d766d60e3ca442651d792c7fe54ea74/zetasql/parser/gen_parse_tree.py#L5434-L5538

TVF has ASTTableClause and ASTModelClause.