Angle brackets in generics and stereotypes not properly parsed

[Enteee]

Describe the bug
To some degree, angle brackets are allowed in generics and stereotypes. For example, the following diagram:

' Angle brackets in generics
class TestGenericsWithAngleBrackets < <G1> >
class TestGenericsWithDoubleAngleBrackets < <<G1>> >

' Angle brackets in stereotypes
class TestStereotypeWithAngleBrackets << <S1> >>
class TestStereotypeWithDoubleAngleBrackets << <<S1>> >>

produces the following diagram:

Currently we do not support this in the parser. Therefore the parsed result is:

[
  {
    "name": "anglebrackets",
    "diagrams": [
      {
        "elements": [
          {
            "comment": "Angle brackets in generics"
          },
          {
            "name": "TestGenericsWithAngleBrackets",
            "title": "TestGenericsWithAngleBrackets",
            "isAbstract": false,
            "members": [],
            "extends_": [],
            "implements_": [],
            "generics": "<G1",
            "stereotype": ""
          },
          {
            "name": "TestGenericsWithDoubleAngleBrackets",
            "title": "TestGenericsWithDoubleAngleBrackets",
            "isAbstract": false,
            "members": [],
            "extends_": [],
            "implements_": [],
            "generics": "<<G1",
            "stereotype": ""
          },
          {
            "comment": "Angle brackets in stereotypes"
          },
          {
            "name": "TestStereotypeWithAngleBrackets",
            "title": "TestStereotypeWithAngleBrackets",
            "isAbstract": false,
            "members": [],
            "extends_": [],
            "implements_": [],
            "generics": "",
            "stereotype": "<S1>"
          },
          {
            "name": "TestStereotypeWithDoubleAngleBrackets",
            "title": "TestStereotypeWithDoubleAngleBrackets",
            "isAbstract": false,
            "members": [],
            "extends_": [],
            "implements_": [],
            "generics": "",
            "stereotype": "<<S1"
          }
        ]
      }
    ]
  }
]

To Reproduce
Steps to reproduce the behavior:

1. Write diagram to file anglebrackets
2. node dist/bin/cli.js -i anglebrackets

Expected behavior
Angle brackets should be parsed properly and added to the generics and/or stereotype property.

Additional context

Double angle brackets:

class TestStereotypeWithDoubleAngleBrackets << <<S1>> >>

Is not properly handled by the original plantuml implementation.