This ticket combines together the need to solve various ways of copying values of fields across the project's entities and assets.

Related tickets: #216 #30 #891 #520

The desired UX:

1. It should be possible to copy/paste any modifiable value of entities and assets.
2. It should be clear on what fields support clipboard.
3. It should be clear on what field we are about to copy/paste when context menu is open.
4. The data should be validated and protected as much as possible to prevent undesirable data changes.
5. It should work with multi-selection (pasting) as well as copying (will copy first selected item's value).
6. History should have a single undo/redo operation for paste, even with multi-selection and multi-pathed fields (e.g.: particle curve sets; arrays of things)
7. User should see what type of value is about to be copied.
8. User should see what type of value is in the clipboard in context menu.

Tasks:

• properly detect types of fields and their variations Clipboard - ability to copy/paste field values in Inspector #1370
• provide context menu on fields and their labels (except input and button dom elements) Clipboard - ability to copy/paste field values in Inspector #1370
• add copy/paste icons beside on fields hover - this will help to find out about feature and provide one-click workflow instead of context menu Clipboard - ability to copy/paste field values in Inspector #1370
• provide some sensible conversion paths between similar types, e.g. rgb <> rgba; asset:* > asset; asset > asset:* (if copied asset of desirable type); etc. Attributes clipboard conversion between different types of fields #1441
• support entity inspector Clipboard - ability to copy/paste field values in Inspector #1370
• support asset inspector Clipboard assets inspector & disabled fields should not be paste-able #1396
• use system's clipboard instead of localStorage by implementing value type detection from a JSON parsed string
• Copy of Entity/Asset from Hierarchy/Asset panel, should also provide valid "Paste" data for fields Attributes clipboard conversion between different types of fields #1441 Copying entities will also add clipboard data editor-api#105
• Entity Layers - is a special case also, not all layers can be cross-copied, e.g. Camera can have Immediate layer, but Render or Light components cannot.
• Entity Render Component meshMaterials - is a frozen length array of materials, a special case
• Entity Anim Component stateGraphAsset - is not bound currently to a path, and is implemented in inspector as a special case
• Implement clipboard for multi-path fields, such as curveset.
• Enum-type fields, should only allow a valid option paste, if trying to paste values that are not within enum, it should not allow pasting. Clipboard to respect enum/select type fields in Inspector #1395
• Disabled fields should not be paste-able. Clipboard assets inspector & disabled fields should not be paste-able #1396

Screenshots:

Context Menu:

Icons (copy/paste) appear when user hovers a field: