[cli] use Deno KV to persist flag values for better DX

[miguelrk]

TLDR: revent flag values like --api-key and --project could be persisted using Deno KV in unique database constructed from the file URL of the project root (e.g. using Deno.openKv(import.meta.url)?)

Context

Refer to the managing state section of the Build a Cross-Platform CLI with Deno in 5 minutes blog post.

Example

This example is also taken from the blogpost and simply used for illustrative purposes of how the code could look like.

- function main(inputArgs: string[]): void {
+ async function main(inputArgs: string[]): Promise<void> {

  const args = parseArguments(inputArgs);

  // If help flag enabled, print help.
  if (args.help) {
    printHelp();
    Deno.exit(0);
  }

  let name: string | null = args.name;
  let color: string | null = args.color;
  let save: boolean = args.save;

+  const kv = await Deno.openKv("/tmp/kv.db");
+  let askToSave = false;

+  if (!name) {
+    name = (await kv.get(["name"])).value as string;
+  }
+  if (!color) {
+    color = (await kv.get(["color"])).value as string;
+  }
+  if (save) {
+    await kv.set(["name"], name);
+    await kv.set(["color"], color);
+  }

  console.log(
    `%c${
      greetings[Math.floor(Math.random() * greetings.length) - 1]
    }, ${name}!`,
    `color: ${color}; font-weight: bold`,
  );
}