Ui fixes (#4917)

* PLT-5089 - Updating modal buttons

* PLT-5090 - Full name and position overflow

* PLT-5093 - Updating modal lists

webapp/sass/components/_modal.scss

@@ -464,24 +464,10 @@
                 float: right;
                 margin-top: 5px;
             }
-
-            .more-modal__list {
-                max-height: calc(100vh - 270px);
-            }
         }
     }
 
     .more-modal {
-        .more-modal__list {
-            height: 100vh;
-            max-height: calc(100vh - 340px);
-        }
-
-        &.more-direct-channels {
-            .more-modal__list {
-                max-height: calc(100vh - 325px);
-            }
-        }
 
         .user-list {
             margin-top: 10px;
@@ -496,7 +482,6 @@
         }
 
         .filter-row {
-            @include clearfix;
             margin: 5px 0 10px;
             width: 300px;
         }
@@ -561,7 +546,11 @@
 .more-modal__list {
     display: flex;
     flex-direction: column;
-    overflow: auto;
+
+    > div {
+        min-height: 100%;
+        overflow: auto;
+    }
 
     .popover & {
         font-size: .95em;
@@ -606,6 +595,7 @@
     .more-modal__actions {
         flex-grow: 0;
         flex-shrink: 0;
+        margin: 5px 0 10px;
         padding-left: 20px;
     }
 
@@ -628,8 +618,7 @@
     .more-modal__row {
         border-bottom: 1px solid $light-gray;
         display: flex;
-        min-height: 70px;
-        padding: 8px 15px;
+        padding: 10px 15px;
     }
 
     p {
@@ -650,16 +639,15 @@
 .filtered-user-list {
     display: flex;
     flex-direction: column;
+    height: calc(90vh - 120px);
     width: 100%;
 
-    .filter-row {
-        flex-grow: 0;
-        flex-shrink: 0;
+    > div {
+        flex: 1;
     }
 
-    .user-list {
-        flex-grow: 1;
-        flex-shrink: 1;
+    .more-modal__list {
+        flex-grow: 500;
     }
 
     .filter-button {
@@ -669,9 +657,6 @@
     }
 
     .filter-controls {
-        @include clearfix;
-        flex-grow: 0;
-        flex-shrink: 0;
         padding: 1em 1.5em 0;
 
         .filter-control__next {