HCL: Support provider scoped functions

[knutwannheden]

As of version 1.8 Terraform supports provider scoped functions as in this example:

terraform {
	required_providers {
		test = {
			source = "hashicorp/test"
		}
	}
}
locals {
	result = provider::test::count_e("cheese")
}

The OpenRewrite HCL parser currently fails to parse this:

Caused by: org.openrewrite.hcl.HclParsingException: Syntax error in file.tf at line 9:18 mismatched input ':' expecting {'}', Identifier, '[', '?', '.'}.
	at org.openrewrite.hcl.HclParser$ForwardingErrorListener.syntaxError(HclParser.java:105)
	... 26 more
Caused by: org.antlr.v4.runtime.InputMismatchException
	at org.antlr.v4.runtime.DefaultErrorStrategy.recoverInline(DefaultErrorStrategy.java:485)
	at org.antlr.v4.runtime.Parser.match(Parser.java:208)
	at org.openrewrite.hcl.internal.grammar.HCLParser.blockExpr(HCLParser.java:1104)
	... 21 more