Remove raw use of parameterized class

Case:
In some classes, you can meet the raw use of parameterized classes.

Example:

• from the PatientProgram class:
  private Set<PatientProgramAttribute> attributes = new LinkedHashSet().

Solution:
In the example, replace LinkedHashSet() with LinkedHashSet<>().

Comments:

• the case of raw use of parameterized classes may also occur in other classes;
• why should not leave the raw use of parameterized class -> https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it

Link to place in code for example class:
https://github.com/openmrs/openmrs-core/blob/master/api/src/main/java/org/openmrs/PatientProgram.java#L54