Resolve lint issues due to new default rules

We could turn these rules off, but it seems that they indicate some important inconsistencies.

A few cases have been ignored inline because they should be investigated in more detail, which is out of scope for this PR:
- Metadata representation components compare `BrowseByDataType` to a `ResourceType`. Could be related to #2949.
- We assume that dynamic form dates are always represented by strings, but they can also be `Date` or `object` according to the library (see da1742ce05/projects/ng-dynamic-forms/core/src/lib/model/dynamic-date-control.model.ts (L5))

.eslintrc.json

@@ -16,6 +16,9 @@
     "dspace-angular-ts",
     "dspace-angular-html"
   ],
+  "ignorePatterns": [
+    "lint/test/fixture"
+  ],
   "overrides": [
     {
       "files": [
@@ -216,6 +219,15 @@
         "@typescript-eslint/no-unsafe-return": "off",
         "@typescript-eslint/restrict-template-expressions": "off",
         "@typescript-eslint/require-await": "off",
+        "@typescript-eslint/no-base-to-string": [
+          "error",
+          {
+            "ignoredTypeNames": [
+              "ResourceType",
+              "Error"
+            ]
+          }
+        ],
 
         "deprecation/deprecation": "warn",