feat: support enum variable bindings in queries

[igdianov]

Given variables json:

{
  "genres": "NOVEL"
}

And the query with enum variable bindings:

query($genre: Genre) {
  Books(where: {
    genre: {EQ: $genre}
  }) {
    select {
      id
      title
      genre
    }
  }
}

Will return:

{
  "data": {
    "Books": {
      "select": [
        {
          "id": 2,
          "title": "War and Peace",
          "genre": "NOVEL"
        },
        {
          "id": 3,
          "title": "Anna Karenina",
          "genre": "NOVEL"
        }
      ]
    }
  }
}

And given variables json:

{
  "genres": ["NOVEL"]
}

And the query with enum list variable bindings:

query($genres: [Genre!]) {
  Books(where: {
    genre: {IN: $genres}
  }) {
    select {
      id
      title
    }
  }
}

will result:

{
  "data": {
    "Books": {
      "select": [
        {
          "id": 2,
          "title": "War and Peace"
        },
        {
          "id": 3,
          "title": "Anna Karenina"
        }
      ]
    }
  }
}

And given variables json:

{
  "genre": "NOVEL"
}

And query with single enum to enum list variable binding:

query($genre: Genre!) {
  Books(where: {
    genre: {IN: [$genre]}
  }) {
    select {
      id
      title
    }
  }
}

Will result in

{
  "data": {
    "Books": {
      "select": [
        {
          "id": 2,
          "title": "War and Peace"
        },
        {
          "id": 3,
          "title": "Anna Karenina"
        }
      ]
    }
  }
}

[codecov]

Codecov Report

Merging #109 into master will increase coverage by 0.05%.
The diff coverage is 92.3%.

@@             Coverage Diff              @@
##             master     #109      +/-   ##
============================================
+ Coverage     65.75%   65.81%   +0.05%     
- Complexity      366      368       +2     
============================================
  Files            37       37              
  Lines          2015     2024       +9     
  Branches        297      299       +2     
============================================
+ Hits           1325     1332       +7     
  Misses          562      562              
- Partials        128      130       +2

Impacted Files	Coverage Δ	Complexity Δ
...a/query/schema/impl/QraphQLJpaBaseDataFetcher.java	71.91% <92.3%> (-0.14%)	113 <1> (+2)
...jpa/query/schema/impl/GraphQLJpaSchemaBuilder.java	86.64% <0%> (+0.18%)	103% <0%> (ø)	⬇️

---

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[codecov]

Codecov Report

Merging #109 into master will increase coverage by 0.05%.
The diff coverage is 92.3%.

@@             Coverage Diff              @@
##             master     #109      +/-   ##
============================================
+ Coverage     65.75%   65.81%   +0.05%     
- Complexity      366      368       +2     
============================================
  Files            37       37              
  Lines          2015     2024       +9     
  Branches        297      299       +2     
============================================
+ Hits           1325     1332       +7     
  Misses          562      562              
- Partials        128      130       +2

Impacted Files	Coverage Δ	Complexity Δ
...a/query/schema/impl/QraphQLJpaBaseDataFetcher.java	71.91% <92.3%> (-0.14%)	113 <1> (+2)
...jpa/query/schema/impl/GraphQLJpaSchemaBuilder.java	86.64% <0%> (+0.18%)	103% <0%> (ø)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8e9d409...d418513. Read the comment docs.