parser: implement Restore for TableOptimizerHint

[exialin]

Impletment Restore and unit test for TableOptimizerHint.

Issue: pingcap/tidb#8532

---

Here is a problem that should be resolved before moving on to SelectStmt. The SelectFields of the following two queries are different:

1. select /*+ TIDB_SMJ(t1) */ * from t1 join t2

*ast.SelectStmt	&{{{{select /*+ TIDB_SMJ(t1) */ * from t1 join t2}}} {[]} 0xc00000f5c0 false 0xc00000a720 <nil> 0xc00000f5f0 <nil> <nil> [] <nil> <nil> none [0xc0000a6d20] false false}
  *ast.TableOptimizerHint	&{{} TIDB_SMJ [t1] 0}
  *ast.TableRefsClause	&{{} 0xc000146080}
    *ast.Join	&{{} {[]} 0xc000054340 0xc000054380 1 <nil> [] false false}
      *ast.TableSource	&{{} 0xc000144090 }
        *ast.TableName	&{{} {[]}  t1 <nil> <nil> []}
      *ast.TableSource	&{{} 0xc000144120 }
        *ast.TableName	&{{} {[]}  t2 <nil> <nil> []}
  *ast.FieldList	&{{} [0xc000058660]}
    *ast.SelectField	&{{} 27 0xc0000a6d70 <nil>  false}

2. select /*+ TIDB_SMJ(`t1`) */ * from t1 join t2

*ast.SelectStmt	&{{{{select /*+ TIDB_SMJ(`t1`) */ * from t1 join t2}}} {[]} 0xc00000f5c0 false 0xc00000a760 <nil> 0xc00000f5f0 <nil> <nil> [] <nil> <nil> none [0xc0000a2d20] false false}
  *ast.TableOptimizerHint	&{{} TIDB_SMJ [t1] 0}
  *ast.TableRefsClause	&{{} 0xc000146080}
    *ast.Join	&{{} {[]} 0xc000054340 0xc000054380 1 <nil> [] false false}
      *ast.TableSource	&{{} 0xc000144090 }
        *ast.TableName	&{{} {[]}  t1 <nil> <nil> []}
      *ast.TableSource	&{{} 0xc000144120 }
        *ast.TableName	&{{} {[]}  t2 <nil> <nil> []}
  *ast.FieldList	&{{} [0xc000058660]}
    *ast.SelectField	&{{} 29 0xc0000a2d70 <nil>  false}

The only difference is SelectField.Offset, which will count the backquotes put by Restore. For this PR we can wrap identifiers in the source SQL text with backquotes, but there are hundreds of select test cases of SelectStmt and some shall not be handled this way. So any suggestion?

[AndrewDi]

@exialin I have meet the same problem as you said in the first place: The only difference is SelectField.Offset, which will count the backquotes put by Restore
So I create a new nodeFieldCleaner visitor to reset offset in PR #153 , you can have a look.

[zier-one]

@exialin I have meet the same problem as you said in the first place: The only difference is SelectField.Offset, which will count the backquotes put by Restore
So I create a new nodeFieldCleaner visitor to reset offset in PR #153 , you can have a look.

I think this is a good solution