Add FolderExistsByServerRelativeUrl method to SharePoint Client (#2898)

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#### Summary <!-- Provide a general summary of your changes -->
Adds FolderExists function to the SharePoint System Application Module

#### Work Item(s) <!-- Add the issue number here after the #. The issue
needs to be open and approved. Submitting PRs with no linked issues or
unapproved issues is highly discouraged. -->
Fixes #2897

Fixes
[AB#565066](https://dynamicssmb2.visualstudio.com/1fcb79e7-ab07-432a-a3c6-6cf5a88ba4a5/_workitems/edit/565066)

src/System Application/App/SharePoint/src/SharePointClient.Codeunit.al

@@ -403,6 +403,16 @@ codeunit 9100 "SharePoint Client"
         exit(SharePointClientImpl.CreateFolder(ServerRelativeUrl, SharePointFolder));
     end;
 
+    /// <summary>
+    /// Checks if a folder exists.
+    /// </summary>
+    /// <param name="ServerRelativeUrl">URL of the folder to check.</param>
+    /// <returns>True if the folder exists; otherwise - false.</returns>
+    procedure FolderExistsByServerRelativeUrl(ServerRelativeUrl: Text): Boolean
+    begin
+        exit(SharePointClientImpl.FolderExistsByServerRelativeUrl(ServerRelativeUrl));
+    end;
+
     /// <summary>
     /// Deletes a folder.
     /// </summary>

src/System Application/App/SharePoint/src/SharePointClientImpl.Codeunit.al

@@ -652,6 +652,25 @@ codeunit 9101 "SharePoint Client Impl."
         exit(true);
     end;
 
+    procedure FolderExistsByServerRelativeUrl(ServerRelativeUrl: Text): Boolean
+    var
+        Result: Text;
+        FolderExists: Boolean;
+    begin
+        SharePointUriBuilder.ResetPath();
+        SharePointUriBuilder.SetMethod('GetFolderByServerRelativeUrl', ServerRelativeUrl);
+        SharePointUriBuilder.SetObject('Exists');
+
+        SharePointRequestHelper.SetAuthorization(Authorization);
+        SharePointOperationResponse := SharePointRequestHelper.Get(SharePointUriBuilder);
+        if not SharePointOperationResponse.GetDiagnostics().IsSuccessStatusCode() then
+            exit(false);
+
+        SharePointOperationResponse.GetResultAsText(Result);
+        ParseFolderExistsByServerRelativeUrlResult(Result, FolderExists);
+        exit(FolderExists);
+    end;
+
     procedure DeleteFolder(OdataId: Text): Boolean
     begin
         //DELETE https://{site_url}/_api/web/GetFolderByServerRelativeUrl('{folder_name}')
@@ -778,5 +797,22 @@ codeunit 9101 "SharePoint Client Impl."
         SharePointOperationResponse.GetResultAsText(Txt);
         exit(true);
     end;
+
+    local procedure ParseFolderExistsByServerRelativeUrlResult(Payload: Text; var FolderExists: Boolean)
+    var
+        JObject: JsonObject;
+        JToken: JsonToken;
+    begin
+        if not JObject.ReadFrom(Payload) then
+            exit;
+
+        if not JObject.Get('value', JToken) then
+            exit;
+
+        if not JToken.IsValue() then
+            exit;
+
+        FolderExists := JToken.AsValue().AsBoolean();
+    end;
     #endregion
 }