Avoid panic by initing universal schema early

[radeksimko]

This fixes a race condition which is difficult to reproduce, but hashicorp/terraform-schema#7 has the relevant panic trace.

This practically delivers on the promise mentioned here

terraform-ls/internal/terraform/rootmodule/root_module.go

Lines 245 to 249 in 612cceb

	err = rm.findAndSetCoreSchema()
	if err != nil {
	rm.logger.Printf("%s: %s - falling back to universal schema",
	rm.Path(), err)
	}

In other words I thought this was already done but I must have missed it in #281

[ghost]

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