feat: 5.1 expressions VSCODE-304 (#359)

Author: mabaasit

syntaxes/mongodb.tmLanguage.json

@@ -2713,6 +2713,15 @@
             }
           }
         },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$searchMeta\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggStageOperators.searchMeta.mongodb"
+            }
+          }
+        },
         {
           "name": "meta.object.member.mongodb",
           "match": "\\$sample\\b",
@@ -2830,6 +2839,24 @@
             }
           }
         },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$documents\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggStageOperators.documents.mongodb"
+            }
+          }
+        },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$densify\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggStageOperators.densify.mongodb"
+            }
+          }
+        },
         {
           "name": "meta.object.member.mongodb",
           "match": "\\$count\\b",
@@ -3217,6 +3244,24 @@
             }
           }
         },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$tsIncrement\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggExpressionOperators.tsIncrement.mongodb"
+            }
+          }
+        },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$tsSecond\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggExpressionOperators.tsSecond.mongodb"
+            }
+          }
+        },
         {
           "name": "meta.object.member.mongodb",
           "match": "\\$toUpper\\b",
@@ -3703,6 +3748,15 @@
             }
           }
         },
+        {
+          "name": "meta.object.member.mongodb",
+          "match": "\\$getField\\b",
+          "captures": {
+            "0": {
+              "name": "keyword.other.aggExpressionOperators.getField.mongodb"
+            }
+          }
+        },
         {
           "name": "meta.object.member.mongodb",
           "match": "\\$floor\\b",