* API
Instead of having a single `load` function that exposes in its API
some elements only applicable to initializing a graph from a templates,
split it into 2 distinct functions: `load` and `initFromTemplate`.
Apply those changes to users of the API (UI, CLI), and simplify Graph
wrapper classes to better align with those concepts.
* Deserialization
Reduce the cognitive complexity of the deserizalization process
by splitting it into more atomic functions, while maintaining the
current behavior.
When the list of recent project files is updated, there is no attempt
to retrieve its thumbnail as the update is said to be "minimal".
This minimal update is justified by the lack of use for the thumbnails
in the Application part of Meshroom. Thumbnails are only useful when
displaying the Homepage, hence their retrieval during Meshroom's
initialization. There is only a need to update them once we want to
display the Homepage again.
The Homepage thus requests an update of the thumbnails before setting
its model. If there have been some updates to the list of recent project
files, the reading of the QSettings is performed again and thumbnails
are retrieved whenever it is possible. Otherwise, nothing happens to
prevent useless readings.
When the elements are being initialized, their sizes is not yet correctly
set. Since the paddings for the `MaterialToolLabelButtons` is computed
dynamically depending on other elements' size, we need to add safeguard
to ensure that the padding can never be larger than the container's size.
