the new method was introduced in #3812 with upgrade path improved in
#4209.

This PR completes polishes this work a bit:

1. The method is renamed to `coerceInputLiteral()` following the naming
convention suggested in #2357, with the other methods to be renamed in
later PRs.
2. The type of the method `GraphQLScalarInputLiteralCoercer` is
exported, which was not done in the initial work. The old
`GraphQLScalarLiteralParser` type is deprecated.

[#3086 rebased on
main](#3086).

Depends on #3812 

@leebyron comments from original PR:

> Factors out input validation to reusable functions:
> 
> * Introduces `validateInputLiteral` by extracting this behavior from
`ValuesOfCorrectTypeRule`.
> * Introduces `validateInputValue` by extracting this behavior from
`coerceInputValue`
> * Simplifies `coerceInputValue` to return early on validation error
> * Unifies error reporting between `validateInputValue` and
`validateInputLiteral`, causing some error message strings to change,
but error data (eg locations) are preserved.
> 
> These two parallel functions will be used to validate default values
> 
> Potentially breaking if you rely on the existing behavior of
`coerceInputValue` to call a callback function, as the call signature
has changed. GraphQL behavior should not change, though error messages
are now slightly different.

Note: also breaking if you rely on the default callback function to
throw. Grossly similar behavior is available with
`validateInputValue()`.

Co-authored-by: Lee Byron <lee.byron@robinhood.com>

[#3049 rebased on
main](#3049).

This is the last rebased PR from the original PR stack concluding with
#3049.

* Rebased: #3809 [Original: #3092]
* Rebased: #3810 [Original: #3074]
* Rebased: #3811 [Original: #3077]
* Rebased: #3812 [Original: #3065]
* Rebased: #3813 [Original: #3086]
* Rebased: #3814 (this PR) [Original: #3049]

Update: #3044 and #3145 have been separated from this stack.

Changes from original PR:
1. `astFromValue()` is deprecated instead of being removed.

@leebyron comments from #3049, the original PR:
> Implements
[graphql/graphql-spec#793](graphql/graphql-spec#793)
> 
> * BREAKING: Changes default values from being represented as an
assumed-coerced "internal input value" to a pre-coerced "external input
value" (See chart below).
> This allows programmatically provided default values to be represented
in the same domain as values sent to the service via variable values,
and allows it to have well defined methods for both transforming into a
printed GraphQL literal string for introspection / schema printing (via
`valueToLiteral()`) or coercing into an "internal input value" for use
at runtime (via `coerceInputValue()`)
> To support this change in value type, this PR adds two related
behavioral changes:
>   
> * Adds coercion of default values from external to internal at runtime
(within `coerceInputValue()`)
> * Removes `astFromValue()`, replacing it with `valueToLiteral()` for
use in introspection and schema printing. `astFromValue()` performed
unsafe "uncoercion" to convert an "Internal input value" directly to a
"GraphQL Literal AST", where `valueToLiteral()` performs a well defined
transform from "External input value" to "GraphQL Literal AST".
> * Adds validation of default values during schema validation.
> Since assumed-coerced "internal" values may not pass "external"
validation (for example, Enum values), an additional validation error
has been included which attempts to detect this case and report a
strategy for resolution.
> 
> Here's a broad overview of the intended end state:
> 
> ![GraphQL Value
Flow](https://user-images.githubusercontent.com/50130/118379946-51ac5300-b593-11eb-839f-c483ecfbc875.png)

---------

Co-authored-by: Lee Byron <lee@leebyron.com>