[eas-cli] Add getters

Added getters for requested platform from string flag value

See: https://linear.app/expo/issue/ENG-9175/update-oclif-in-eas-cli

packages/eas-cli/src/platform.ts

@@ -1,4 +1,5 @@
 import { Platform } from '@expo/eas-build-job';
+import { Errors } from '@oclif/core';
 
 import { AppPlatform } from './graphql/generated';
 import { promptAsync } from './prompts';
@@ -20,6 +21,27 @@ export enum RequestedPlatform {
   All = 'all',
 }
 
+export function maybeGetRequestedPlatform(
+  requestedPlatformString: string | undefined
+): RequestedPlatform | undefined {
+  if (!requestedPlatformString) {
+    return undefined;
+  }
+  return Object.values(RequestedPlatform).find(
+    requestedPlatform => requestedPlatform === requestedPlatformString
+  );
+}
+
+export function getRequestedPlatform(requestedPlatformString: string): RequestedPlatform {
+  const parsedRequestedPlatform = Object.values(RequestedPlatform).find(
+    requestedPlatform => requestedPlatform === requestedPlatformString
+  );
+  if (!parsedRequestedPlatform) {
+    Errors.error(`"${requestedPlatformString}" RequestedPlatform does not exist`, { exit: 1 });
+  }
+  return parsedRequestedPlatform;
+}
+
 export const requestedPlatformDisplayNames: Record<RequestedPlatform, string> = {
   [RequestedPlatform.Android]: 'Android',
   [RequestedPlatform.Ios]: 'iOS',