Fragment args 2024 amendments

[JoviDeCroock]

These amendments are made from comments on the implementation PR and alterations from the new implementation

• Changing fragment-key to just be fragment-name Fragment Arguments Reference Implementation graphql/graphql-js#3835 (comment)
• Removing the substitution logic and going closer to the coerce logic we use in the general flow

In general the biggest changes are that we introduce fragmentVariableValues which will be on the groupedFieldSet, these are derived from the arguments in scope of the fragmentDefinition where this field is used.

We introduce localFragmentVariables which as we are traversing down fragment-spreads are a coerced set of variables i.e.

query($b: String!, $c: String!) {
  field3(b: $b) ## uses b from variable-values
  ...A(a: "A", b: "B")
}

fragment A on X ($a: String!, $b: String!) {
  field(a: $a) ## uses $a from localVariableValues
  field2(c: $c) ## we have access to variableValues so we take c from there
  ...B(b: $b) ## uses $b from localVariableValues
}

fragment B on X ($b: String!) {
  ## This fragment has access to $b and $c but not to $a
  field4(b: $b) ## uses $b from localVariableValues
}

Last but not least we introduce getArgumentValuesFromSpread which looks at the spread and fragment-definition and establishes a coerced set of localVariableValues.

Not sure how to call GraphQL WG reviewers here 😅

[JoviDeCroock]

Closing as there's a PR open on the main spec repo