ui: upgrade to blueprintjs6

packages/ui-default/pages/problem_config.page.styl

@@ -12,10 +12,10 @@
   .textbox,.select
     margin: 0
   
-  .bp5-tab-panel
+  .bp6-tab-panel
     margin-top: 5px
 
-  .bp5-dialog
+  .bp6-dialog
     font-family: var(--code-font-family)
     background: #fff
 
@@ -23,7 +23,7 @@
       font-size: 0.875rem
       color: #666
 
-    .bp5-dialog-footer-fixed
+    .bp6-dialog-footer-fixed
       border-top: 0
 
       .button
@@ -32,7 +32,7 @@
   input::placeholder
     color: rgba(95,107,124,.6)!important
 
-  .bp5-input-group
+  .bp6-input-group
     input
       appearance: none
       display: block
@@ -49,10 +49,10 @@
       transition-timing-function: cubic-bezier(0.215, 0.61, 0.355, 1)
       box-shadow: none
 
-  .bp5-tag.bp5-minimal
+  .bp6-tag.bp6-minimal
     background: transparent
   
-  .bp5-input-action
+  .bp6-input-action
       pointer-events: none
 
   .problem-config-form