feat: add support for work item types

What does this MR do and why?

feat: add support for work item types

Add support for work item types using the type parameter. Supported types include: Issue, Incident, Requirement, TestCase, Task, Ticket, Objective, KeyResult, Epic and MergeRequest.

Related issue #29 (closed)

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

src/analyzer/sources/issues.rs

+use super::shared::type_field_types;
 use crate::types::{
     Field, Field::*, FieldType, FieldType::*, ReferenceType::*, RelationshipType::*,
 };
@@ -27,6 +28,8 @@ pub fn is_valid_field(field: &Field) -> bool {
 
 pub fn field_types(field: &Field) -> Vec<FieldType> {
     match field {
+        Type => type_field_types(),
+
         Assignee => vec![
             StringLike,
             ReferenceLike(UserRef),
@@ -63,10 +66,6 @@ pub fn field_types(field: &Field) -> Vec<FieldType> {
             ReferenceLike(IterationRef),
         ],
         Epic => vec![StringLike, NumberLike, Nullable],
-        Type => vec![Strict(Box::new(EnumLike(vec![
-            "Issue".into(),
-            "MergeRequest".into(),
-        ])))],
         Group | Project => vec![Strict(Box::new(StringLike))],
         Opened | Closed => vec![DateLike, BooleanLike],
         Created | Updated | Due => vec![DateLike],