HCK-10528: updated conversion and derivment configs to handle nchar and char max length (#48)

<!--do not remove this marker, its needed to replace info when ticket
title is updated -->
<!--jira-description-action-hidden-marker-start-->

<table>
<td>
<a href="https://hackolade.atlassian.net/browse/HCK-10528"
title="HCK-10528" target="_blank"><img alt="Sub-bug"
src="https://hackolade.atlassian.net/rest/api/2/universal_avatar/view/type/issuetype/avatar/10303?size=medium"
/>HCK-10528</a> [DB2] char/nchar datatypes with max length incorrect
derived/converted from/to Poly
  </td></table>
  <br />
 

<!--jira-description-action-hidden-marker-end-->
## Content

Updated conversion and derivment configs to handle nchar and char max
length

Author: NazarKovtun1

polyglot/adapter.json

@@ -45,6 +45,16 @@
 					"length": 32704
 				}
 			},
+			{
+				"from": {
+					"type": "varchar",
+					"mode": "char",
+					"hasMaxLength": true
+				},
+				"to": {
+					"length": 255
+				}
+			},
             {
 				"from": {
 					"type": "nvarchar",
@@ -54,6 +64,16 @@
 					"length": 32704
 				}
 			},
+			{
+				"from": {
+					"type": "nvarchar",
+					"mode": "nchar",
+					"hasMaxLength": true
+				},
+				"to": {
+					"length": 255
+				}
+			},
             {
 				"from": {
 					"type": "binary",

polyglot/convertAdapter.json

@@ -62,7 +62,25 @@
 				"to": {
 					"hasMaxLength": true
 				}
-			}
+			},
+			{
+				"from": {
+					"mode": "char",
+					"length": 255
+				},
+				"to": {
+					"hasMaxLength": true
+				}
+			},
+			{
+				"from": {
+					"mode": "nchar",
+					"length": 255
+				},
+				"to": {
+					"hasMaxLength": true
+				}
+			},
 		]
 	}
 }