message: Move tooltips to button
  - Fixes
diff: <ng-container matColumnDef="status">
  <mat-header-cell *matHeaderCellDef translate>LABEL_STATUS</mat-header-cell>
  <mat-cell *matCellDef="let challenge">
  - <button mat-raised-button [color]="challenge.solved ? 'accent': 'primary'" [disabled]="challenge.disabledEnv">
  - <span [hidden]="challenge.solved || challenge.disabledEnv" id="{{challenge.name}}.notSolved"
  - class="not-solved"
  - (click)="openHint(challenge)"
  + <button mat-raised-button [color]="challenge.solved ? 'accent': 'primary'"
  + [hidden]="challenge.solved || challenge.disabledEnv" (click)="openHint(challenge)"
  matTooltip="{{ showChallengeHints ? challenge.hint : null }}" matTooltipPosition="above">
  + <span id="{{challenge.name}}.notSolved" class="not-solved">
  <i class="fas fa-book" aria-hidden="true"
  [hidden]="!showChallengeHints || !(challenge.hint || challenge.hintUrl)"></i>
  {{"STATUS_UNSOLVED" | translate}}
  </span>
  - <span [hidden]="!challenge.solved || challenge.disabledEnv" id="{{challenge.name}}.solved" class="solved"
  - (click)="repeatNotification(challenge)"
  + </button>
  + <button mat-raised-button [color]="challenge.solved ? 'accent': 'primary'"
  + [hidden]="!challenge.solved || challenge.disabledEnv" (click)="repeatNotification(challenge)"
  matTooltip="{{ allowRepeatNotifications ? ('NOTIFICATION_RESEND_INSTRUCTIONS' | translate) : null }}"
  matTooltipPosition="above">
  + <span id="{{challenge.name}}.solved" class="solved">
  <i class="far fa-flag" aria-hidden="true" [hidden]="!allowRepeatNotifications"></i>
  {{"STATUS_SOLVED" | translate}}
  </span>
  - <span [hidden]="!challenge.disabledEnv" id="{{challenge.name}}.unavailable" class="unavailable"
  + </button>
  + <button mat-raised-button [color]="challenge.solved ? 'accent': 'primary'" [disabled]="challenge.disabledEnv"
  + [hidden]="!challenge.disabledEnv"
  matTooltip="{{ challenge.hint }}" matTooltipPosition="above">
  + <span id="{{challenge.name}}.unavailable" class="unavailable">
  <i class="fab fa-{{challenge.disabledEnv?.toLowerCase()}}" aria-hidden="true"></i>
  {{"STATUS_UNAVAILABLE" | translate}}
  </span>
  