ci: add problem matcher for patch conflict output (#47224)

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: David Sanders <dsanders11@ucsbalum.com>

.github/actions/checkout/action.yml

@@ -80,6 +80,9 @@ runs:
       else
         echo "The cross mount cache has $freespace_human free space - continuing"
       fi
+  - name: Add patch conflict problem matcher
+    shell: bash
+    run: echo "::add-matcher::src/electron/.github/problem-matchers/patch-conflict.json"
   - name: Gclient Sync
     if: steps.check-cache.outputs.cache_exists == 'false'
     shell: bash
@@ -128,7 +131,11 @@ runs:
           echo "No changes to patches detected"
         fi
       fi
-
+  - name: Remove patch conflict problem matcher
+    shell: bash
+    run: |
+      echo "::remove-matcher owner=merge-conflict::"
+      echo "::remove-matcher owner=patch-conflict::"
   # delete all .git directories under src/ except for
   # third_party/angle/ and third_party/dawn/ because of build time generation of files
   # gen/angle/commit.h depends on third_party/angle/.git/HEAD

.github/problem-matchers/patch-conflict.json

@@ -0,0 +1,24 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "merge-conflict",
+      "pattern": [
+        {
+          "regexp": "^CONFLICT\\s\\(\\S+\\): (Merge conflict in \\S+)$",
+          "message": 1
+        }
+      ]
+    },
+    {
+      "owner": "patch-conflict",
+      "pattern": [
+        {
+          "regexp": "^error: (patch failed: (\\S+):(\\d+))$",
+          "message": 1,
+          "file": 2,
+          "line": 3
+        }
+      ]
+    }
+  ]
+}