Add internal attributes in "Notes" tab

[cbentejac]

Description

This PR adds support for internal attributes, which are attributes that exist for all nodes independently from their type. Internal attributes are displayed in the "Notes" tab of the graph editor (also added in this PR) and can be set for each node individually and independently.

Four internal attributes are added with this PR: comments/invalid comments (to write some comments regarding a node), label (to rename a node), and color (to change a node's color).

Features list

• [X] Add support for internal attributes (attributes that will appear in the "Notes" tab)
• [X] Support multiline text field parameters and color selector text field parameters
• [X] Add a first set of internal parameters: "comments", "invalid comments", "label" and "color"

[cbentejac]

Need to deal with node upgrade of internal attributes.

Done

[fabiencastan]

• [x] If we rename one internalAttribute, the upgrade is not working fine.
• [x] Add an icon on nodes with comments (with the comment in tooltip)

[mh0g]

On windows via the gui:

• colors tested, works
• invalidation tested, works
• renaming node tested, works

Also tested with meshroom batch

Note: would it be possible to include the custom name (if any), in the status file created by each of the node? As the folder name is not affected by the pr, this could be a convenient way to better differentiate two nodes of the same types.

[mh0g]

Does not break backward compatibility on projects from current develop .