Implement for_each and each.* extensions (#145)

This provides completion hints inside blocks for `for_each` and `each.*` references within `resource`, `data` and `module` blocks anywhere the `for_each` meta-argument is supported. It detects if `for_each` is used already and does not suggest duplicates and detects when it is necessary to provide `each.*` completions. This does not complete the values for `each.key` and `each.value`, e.g. `each.value.something`.

This also provides hover support for `for_each` and `each.*` references using the documentation as source.

This also provides semantic token support for `for_each` and `each.*` references.

Closes hashicorp/terraform-ls#861

decoder/body_candidates.go

@@ -26,6 +26,14 @@ func (d *PathDecoder) bodySchemaCandidates(body *hclsyntax.Body, schema *schema.
  candidates.List = append(candidates.List, attributeSchemaToCandidate("count", countAttributeSchema(), editRng))
  }
  }
+
+ if schema.Extensions.ForEach {
+ // check if for_each attribute is already declared, so we don't
+ // suggest a duplicate
+ if _, present := body.Attributes["for_each"]; !present {
+ candidates.List = append(candidates.List, attributeSchemaToCandidate("for_each", forEachAttributeSchema(), editRng))
+ }
+ }
  }
 
  if len(schema.Attributes) > 0 {