Add eez-flow-template-stm32f746g-disco

[mvladic]

Current repository location: https://envox.hr/gitea/goran-mahovlic/eez-flow-template-stm32f746g-disco

Actions:

• Add eez-framework as submodule
• Should be upgraded to the latest version of eez-framework
• Create repository on github and make gitea repository as link to the gihub repository.
• Add eez-flow-template topic to the gitea repository so it is included in Studio list of template repositories.

[goran-mahovlic]

We need to check if everything else is working but stm32f746g-disco is now working in this branch

https://envox.hr/gitea/goran-mahovlic/eez-flow-template-stm32f746g-disco/src/branch/dev-g

eez-framework is now added as submodule and points to eez-framework dev-g branch
it is latest version with define addons for this board