Support allow-discrete

[konieckropka]

VS Code doesn't suggest allowed properties in transition-behavior:

Expected:

• show suggestion allow-discrete
• show suggestion normal
• show global values inherit, initial, revert, revert-layer, unset;

Current behavior:

Also the whole line is not colored properly like other properties (in example white instead of blue):

However when typing "transition-behavior" VS Code properly suggest that property:

Proper suggestions should be as follow (allow-discrete or normal)

Source: https://developer.mozilla.org/en-US/docs/Web/CSS/transition-behavior

Transition-behavior is Baseline 2024 so every major browser supports it.