This patch introduces functions same as rb_hash_has_key()
to reduce rb_funcall() calling because it has a overhead.

−               | before   | after    | result
--               | --       | --       | --
JSON.parse       | 302.109k | 343.547k | 1.14x
JSON.generate    | 569.705k | 568.668k | −

### Environment
- MacBook Air (M1, 2020)
- macOS 12.0 beta
- Apple M1
- Ruby 3.0.2

### Before
```
Warming up --------------------------------------
          JSON.parse    30.347k i/100ms
       JSON.generate    56.987k i/100ms
Calculating -------------------------------------
          JSON.parse    302.109k (± 0.2%) i/s -      1.517M in   5.022546s
       JSON.generate    569.705k (± 0.2%) i/s -      2.849M in   5.001462s
```

### After
```
Warming up --------------------------------------
          JSON.parse    35.109k i/100ms
       JSON.generate    57.611k i/100ms
Calculating -------------------------------------
          JSON.parse    343.547k (± 0.3%) i/s -      1.720M in   5.007637s
       JSON.generate    568.668k (± 0.3%) i/s -      2.881M in   5.065486s
```

### Test code
```ruby
require 'benchmark/ips'
require 'json'

json =<<-EOF
{
  "$id": "https://example.com/person.schema.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Person",
  "type": "object",
  "properties": {
    "firstName": {
      "type": "string",
      "description": "The person's first name."
    },
    "lastName": {
      "type": "string",
      "description": "The person's last name."
    },
    "age": {
      "description": "Age in years which must be equal to or greater than zero.",
      "type": "integer",
      "minimum": 0
    }
  }
}
EOF

Benchmark.ips do |x|
  x.report('JSON.parse') { JSON.parse(json, symbolize_names: true) }

  data = JSON.parse(json, symbolize_names: true)
  x.report('JSON.generate') { JSON.generate(json, indent: "\t") }
end
```