Don't crash when update is used as a modifier outside cc

[odersky]

We now treat update like erased and consume. The error message is still not great, maybe something can be done about that.

[hamzaremmal]

Relates to #24371

[hamzaremmal]

Note that this work because we revive a dead path in the Scanner.

scala3/compiler/src/dotty/tools/dotc/parsing/Scanners.scala

Lines 1228 to 1234 in 32bfd5f

	def isSoftModifier: Boolean =
	token == IDENTIFIER
	&& (softModifierNames.contains(name)
	|| name == nme.erased && erasedEnabled
	|| name == nme.tracked && trackedEnabled
	|| name == nme.update && Feature.ccEnabled
	|| name == nme.consume && Feature.ccEnabled)

Before, we matched in line 1230 but now we will match in line 1233.