feat(kubernetes/shell): kubectl web shell and kubeconfig functionality EE-448 (#5229)

* feat(kubernetes/shell): backport kubectl shell backend functionality EE-849 (#5168)

* backported core backend kubectl shell functionality

* - backported kubectl shell unit tests
- backported k8s cli interface update
- backported k8s client library fake patch

* refactored backend to match EE

* fixed test error typo

* GetServiceAccountName -> GetServiceAccount - making the function reusable in multiple contexts

* feat(kubernetes/shell): backport kubeconfig generation backend functionality EE-1004 (#5213)

* backported core backend kubectl shell functionality

* refactored backend to match EE

* - backported kubernetes backend handler implementation
- backported kubernetes config endpoint
- backported kubeconfig file generation
- backported kubeconfig and yaml unit tests
- backported updates to kubeclient interfaces

* feat(app): kubectl shell ui backport EE-927 (#5221)

* Kubectl UI backport to CE

* fix authentication redirect issue

* comment out redirect function

* fix shell full width & change name of shell

* disable button when terminal connected

* fixed whitespace changes for css

* fixed whitespace changes for html

* linting fixes

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* feat(kubernetes/shell): backport of kubeconfig export functionality EE-926 (#5228)

* EE backport of kubeconfig UI functionality

* using angularjs constant instead of hardcoded URL

* updated portainer kubectl shell image

* fix kubectl button position issue in ce

* fix pod keep running when switching page

* feat(app): Kubectl shell ui EE-833 EE-1099 (#5271)

* fix kubectl shell css

* fix mini css issue

* fix tech issue for ui changes from review

* delete unuse file

* - refactored variable names
- restored content-wrapper scroll
- created object to store wrapper css

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* addressing PR issues

* fix required changes from tech reviews (#5319)

* fix required changes from tech reviews

* remove unuse css variable

* component refactor accoridng to PR and style guidelines

Co-authored-by: zees-dev <dev.786zshan@gmail.com>

* removed redundant dockerhub api endpoint variable

* - autoHeight -> terminal-window
- removed redundant try-catch
- saving config.yaml file as config

* fix(kube/shell): show error on failure

* fixed default https bug

* resolved merge conflicts

Co-authored-by: Richard Wei <54336863+WaysonWei@users.noreply.github.com>
Co-authored-by: richard <richard@richards-iMac-Pro.local>
Co-authored-by: Chaim Lev-Ari <chiptus@gmail.com>

app/kubernetes/components/kubectl-shell/kubectl-shell.html

@@ -0,0 +1,27 @@
+<button type="button" class="btn btn-xs btn-primary" ng-click="$ctrl.connectConsole()" ng-disabled="$ctrl.state.shell.connected">
+  <i class="fa fa-terminal" style="margin-right: 2px;"></i>
+  kubectl shell
+</button>
+
+<div ng-if="$ctrl.state.checked" class="{{ $ctrl.state.css }}-kubectl-shell">
+  <div class="shell-container">
+    <div class="shell-item"><i class="fas fa-terminal" style="margin-right: 5px;"></i>kubectl shell</div>
+    <div ng-if="$ctrl.state.isHTTPS" class="shell-item-center">
+      <a href="" ng-click="$ctrl.downloadKubeconfig()"><i class="fas fa-file-download" style="margin-right: 5px;"></i>Download Kubeconfig</a>
+    </div>
+    <div class="shell-item-right">
+      <i class="fas fa-redo-alt" ng-click="$ctrl.screenClear();"></i>
+      <i class="fas {{ $ctrl.state.icon }}" ng-click="$ctrl.miniRestore();"></i>
+      <i class="fas fa-times" ng-click="$ctrl.disconnect()"></i>
+    </div>
+  </div>
+  <div>
+    <div style="padding: 0px;">
+      <div>
+        <div id="terminal-container" class="terminal-container">
+          <div style="position: fixed; color: #fff;">Loading Terminal...</div>
+        </div>
+      </div>
+    </div>
+  </div>
+</div>