Switch deprecated {{hasBlock}} to (has-block)

no issue

See https://github.com/emberjs/rfcs/blob/master/text/0689-deprecate-has-block.md

ghost/admin/app/components/gh-fullscreen-modal.hbs

@@ -1,7 +1,7 @@
 <LiquidWormhole @class="fullscreen-modal-container">
     <div class="fullscreen-modal-background" {{action "clickOverlay"}}></div>
     <div class={{this.modalClasses}}>
-        {{#if hasBlock}}
+        {{#if (has-block)}}
           {{yield}}
         {{else}}
             {{#let (component this.modalPath) as |ModalComponent|}}

ghost/admin/app/components/gh-infinity-loader.hbs

@@ -4,7 +4,7 @@
         class="{{this.loaderClassNames}}{{if this.viewportEntered " in-viewport"}}{{if this.isDoneLoading " reached-infinity"}}"
         data-test-infinity-loader>
 
-        {{#if hasBlock}}
+        {{#if (has-block)}}
             {{yield this.infinityModelContent}}
         {{else}}
             {{#if this.isDoneLoading}}

ghost/admin/app/components/gh-task-button.hbs

@@ -1,4 +1,4 @@
-{{#if hasBlock}}
+{{#if (has-block)}}
     {{yield (hash
         isIdle=this.isIdle
         isRunning=this.isRunning