[REFACTOR] Reorganize the CSS rules

[tbouffard]

This particularly applies to Happy Path rules but review all css rules.

happy-path rules
There is no need to declare class by types. The CSS classname should always be the same and the CSS rule should required both the BPMN CSS classes and the specific classes. For intance bpmn-type-activity.happy-path

The from/to stroke are not needed in the animation if the grow keyframes (same values for from and to), if the value was correctly set in the CSS rule referencing this keyframes declaration

icpm-demo-2022/src/assets/styles.css

Lines 175 to 189 in 227ddbb

	@keyframes grow {
	from {
	stroke-dashoffset: 100%;
	stroke-dasharray: 100%;
	stroke: var(--stroke);
	stroke-width: var(--stroke-width);
	fill: var(--fillStart);
	}
	to {
	stroke-dashoffset: 0;
	stroke: var(--stroke);
	stroke-width: var(--stroke-width);
	fill: var(--fillEnd);
	}
	}