Only download tailwind binaries if none are present

[sbrow]

TL; DR - Would you be open to a PR that makes tailwind:build update less aggressively?

I came to work today to a failing tailwind build. While investigating this problem,
I discovered that my ./var/tailwind directory contained at least 4 different versions of
the tailwind binary, which I presume means that this bundle always looks for and downloads the latest version
of tailwind when running console tailwind:build.

While I understand that not everyone likes to be chained to strictly pinned dependencies (praise be to Nix), I think that it would be a more sensible default to check if there is any version
of tailwind already downloaded, and if so, only download a different one if a pinned version has been configured, and none of the downloaded versions match the configuration.

Suddenly updating users to a major revision without any notice is a bit jarring.

Let me know if this sounds good to you, and thank you for letting us pin a specific version.

Below is some pseudo code of what I'm thinking:

<?php

/**
  * Downloads tailwind if necessary.
  * @return The version of binary that will be used.
  * /
function maybe_download_tailwindss($user_config): string {
    $downloaded_versions = find_downloaded_tailwind_binaries();
    $pinned_version = $user_config->binary_version;

    if ($pinned_version) {  
        if (in_array($pinned_version, $downloaded_versions)) {
            return $pinned_version;
        } else {
            return download_tailwind($pinned_version);
        }
    } else {
        if (empty($downloaded_versions)) {
            return download_tailwind('latest');
        } else {
            // Here you could check if a newer version exists upstream and inform the user.

            return end($downloaded_versions); // assuming versions are sorted in ascending order.
        }
    }
}

[kbond]

Yep, I can see the value in this.