Implement LVGL with SDL for simulator (#16)

* Implemented LVGL with SDL for simulator

* cleanup

* added SDL to build

* build fix

* mutex fixes

* sim app cleanup and improvements

* docs updated

* fix for sdl?

* fix for SDL cmake setup

libs/lv_drivers/.github/auto-comment.yml

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+# Comment to a new issue.
+pullRequestOpened: |
+  Thank you for raising your pull request.
+  
+  To ensure that all licensing criteria is met all repositories of the LVGL project apply a process called DCO (Developer's Certificate of Origin). 
+  
+  The text of DCO can be read here: https://developercertificate.org/
+  For a more detailed description see the [Documentation](https://docs.lvgl.io/latest/en/html/contributing/index.html#developer-certification-of-origin-dco) site.
+  
+  By contributing to any repositories of the LVGL project you state that your contribution corresponds with the DCO.
+  
+  No further action is required if your contribution fulfills the DCO. If you are not sure about it feel free to ask us in a comment. 

libs/lv_drivers/.github/stale.yml

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+# Number of days of inactivity before an issue becomes stale
+daysUntilStale: 21
+# Number of days of inactivity before a stale issue is closed
+daysUntilClose: 7
+# Issues with these labels will never be considered stale
+exemptLabels:
+  - architecture
+  - pinned
+# Label to use when marking an issue as stale
+staleLabel: stale 
+# Comment to post when marking an issue as stale. Set to `false` to disable
+markComment: >
+  This issue or pull request has been automatically marked as stale because it has not had
+  recent activity. It will be closed if no further activity occurs. Thank you
+  for your contributions.
+# Comment to post when closing a stale issue. Set to `false` to disable
+closeComment: false