feat: Add parameters to configure the executors

src/executors/linux_android.yml

@@ -1,7 +1,24 @@
+parameters:
+  java_options:
+    description: Java command options. Note that setting this will override the default options so you might need to supply those as well.
+    type: string
+    default: '-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -Xms1048m -Xmx2048m'
+  gradle_options:
+    description: Gradle command options. Note that setting this will override the default options so you might need to supply those as well.
+    type: string
+    default: '-Dorg.gradle.daemon=false -Dorg.gradle.jvmargs="-XX:+HeapDumpOnOutOfMemoryError -Xmx2048m"'
+  build_threads:
+    description: The number of build threads to use.
+    type: integer
+    default: 2
+  resource_class:
+    description: Changes the resource class of the executor. Requires a support request to enable the resource_class parameter. See https://circleci.com/docs/2.0/configuration-reference/#resource_class
+    type: string
+    default: medium
 docker:
   - image: reactnativecommunity/react-native-android
-resource_class: 'medium'
+resource_class: <<parameters.resource_class>>
 environment:
-  - _JAVA_OPTIONS: '-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -Xmx2048m'
-  - GRADLE_OPTS: '-Dorg.gradle.daemon=false -Dorg.gradle.jvmargs="-XX:+HeapDumpOnOutOfMemoryError -Xmx2048m"'
-  - BUILD_THREADS: 2
+  - _JAVA_OPTIONS: <<parameters.java_options>>
+  - GRADLE_OPTS: <<parameters.gradle_options>>
+  - BUILD_THREADS: <<parameters.build_threads>>

src/executors/linux_js.yml

@@ -1,4 +1,14 @@
+parameters:
+  node_version:
+    description: The version of Node to use. This can be either a major version ("8"), a major and minor ("8.4"), or a fully qualified version ("8.4.1").
+    type: string
+    default: '8'
+  resource_class:
+    description: Changes the resource class of the executor. Requires a support request to enable the resource_class parameter. See https://circleci.com/docs/2.0/configuration-reference/#resource_class
+    type: string
+    default: medium
 docker:
-  - image: circleci/node:8
+  - image: circleci/node:<<parameters.node_version>>
+resource_class: <<parameters.resource_class>>
 environment:
   - PATH: '/opt/yarn/yarn-v1.5.1/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'

src/executors/macos.yml

@@ -1,3 +1,12 @@
+parameters:
+  xcode_version:
+    description: The version of Xcode to use. See here for the list of supported versions https://circleci.com/docs/2.0/testing-ios/#supported-xcode-versions
+    type: string
+    default: '10.1.0'
+  resource_class:
+    description: Changes the resource class of the executor. Requires a support request to enable the resource_class parameter. See https://circleci.com/docs/2.0/configuration-reference/#resource_class
+    type: string
+    default: medium
 macos:
-  xcode: '10.1.0'
-resource_class: 'medium'
+  xcode: <<parameters.xcode_version>>
+resource_class: <<parameters.resource_class>>