Explore: fix render issues in split view

- avoid line wrap in row tools (add/remove/clear)
- avoid text overflow in query field

public/sass/components/_slate_editor.scss

@@ -2,6 +2,7 @@
   font-size: $font-size-root;
   font-family: $font-family-monospace;
   height: auto;
+  word-break: break-word;
 }
 
 .slate-query-field-wrapper {

public/sass/pages/_explore.scss

@@ -126,7 +126,7 @@
 }
 
 .query-row-tools {
-  width: 6rem;
+  white-space: nowrap;
 }
 
 .query-row-field {