Add timestamp filtering to workflow instance list

A new TimestampFilterModel class was added and integrated into the WorkflowInstanceList component for enhanced data filtering based on timestamps. The UI was also adjusted to accommodate these changes, allowing users to select and apply timestamp filters. Modifications were also made to maintain privacy by changing a few collection properties from public to private.

src/framework/Elsa.Studio.Shell/wwwroot/css/shell.css

@@ -16,20 +16,12 @@
 /*****************************************************
 * CSS hacks for the MudBlazorExtensions components
 ******************************************************/
-.mud-select-extended {
-    min-width: 100px;
-}
-
-.mud-select-extended .mud-input-slot  {
-    min-height: 2.1em !important;
+.mud-select.timespan-operator {
+    min-width: 150px;
 }
 
-/*****************************************************
-* Environment Picker
-******************************************************/
-.elsa-environment-picker .mud-input > input.mud-input-root-outlined, div.mud-input-slot.mud-input-root-outlined {
-    padding-top: 11px;
-    padding-bottom: 11px;
+.mud-select-extended {
+    min-width: 100px;
 }
 
 /*****************************************************

src/modules/Elsa.Studio.Workflows/Components/WorkflowInstanceList/Models/TimestampFilter.cs

@@ -0,0 +1,30 @@
+using Elsa.Api.Client.Shared.Enums;
+using JetBrains.Annotations;
+
+namespace Elsa.Studio.Workflows.Components.WorkflowInstanceList.Models;
+
+/// <summary>
+/// Represents a timestamp filter used for filtering data based on a specified timestamp column and operator.
+/// </summary>
+public class TimestampFilterModel
+{
+    /// <summary>
+    /// Gets or sets the column to filter by.
+    /// </summary>
+    public string Column { get; set; } = default!;
+
+    /// <summary>
+    /// Gets or sets the operator to use for filtering.
+    /// </summary>
+    public TimestampFilterOperator Operator { get; set; }
+
+    /// <summary>
+    /// Gets or sets the date to filter by.
+    /// </summary>
+    public string Date { get; set; }
+
+    /// <summary>
+    /// Gets or sets the time to filter by.
+    /// </summary>
+    public string Time { get; set; }
+}

src/modules/Elsa.Studio.Workflows/Components/WorkflowInstanceList/Models/WorkflowInstanceRow.cs

@@ -14,4 +14,5 @@ internal record WorkflowInstanceRow(
     int IncidentCount,
     DateTimeOffset CreatedAt,
     DateTimeOffset? UpdatedAt,
-    DateTimeOffset? FinishedAt);
+    DateTimeOffset? FinishedAt
+);