Revise serde mapping of ruststep::ast

[termoshtt]

Split from #220

• Do not use RecordDeserializer for Parameter::Ref → Do not use RecordDeserializer for Name #224
• Fix "map" to "newtype_struct" for ast::Name → Do not use RecordDeserializer for Name #224
• Rename Record into SimpleEntityInstance
• Introduce ComplexEntityInstance struct and implement Deserializer
• Change mapping of Parameter::Typed and Record into "struct" in serde model

[termoshtt]

This should be remained as "Record"

[termoshtt]

ENTITY person;
  name: STRING;
END_ENTITY;

ENTITY employee SUBTYPE OF (person);
  pay: INTEGER;
END_ENTITY;

ENTITY student SUBTYPE OF (person);
  school_name: STRING;
END_ENTITY;

In this case following all instances are complex entity instance

/* internal mapping */
#1 = EMPLOYEE('Hitori Goto', 10);
#2 = STUDENT('Ikuno Kita', 'Shuka');

/* external mapping */
#3 = (PERSON('Hitori Goto') EMPLOYEE(10));
#4 = (PERSON('Ikuno Kita') STUDENT('Shuka));
#5 = (PERSON('Nizika Iziti') EMPLOYEE(15) STUDENT('Simokitazawa'))

Thus, we should not use the naming "simple entity instance" for A(1) and "complex entity instance" (A(1) B(2)) is not correct