Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/vendor/phpunit/php-timer/README.md

@@ -0,0 +1,106 @@
+# phpunit/php-timer
+
+[![Latest Stable Version](https://poser.pugx.org/phpunit/php-timer/v/stable.png)](https://packagist.org/packages/phpunit/php-timer)
+[![CI Status](https://github.com/sebastianbergmann/php-timer/workflows/CI/badge.svg)](https://github.com/sebastianbergmann/php-timer/actions)
+[![Type Coverage](https://shepherd.dev/github/sebastianbergmann/php-timer/coverage.svg)](https://shepherd.dev/github/sebastianbergmann/php-timer)
+[![codecov](https://codecov.io/gh/sebastianbergmann/php-timer/branch/main/graph/badge.svg)](https://codecov.io/gh/sebastianbergmann/php-timer)
+
+Utility class for timing things, factored out of PHPUnit into a stand-alone component.
+
+## Installation
+
+You can add this library as a local, per-project dependency to your project using [Composer](https://getcomposer.org/):
+
+```
+composer require phpunit/php-timer
+```
+
+If you only need this library during development, for instance to run your project's test suite, then you should add it as a development-time dependency:
+
+```
+composer require --dev phpunit/php-timer
+```
+
+## Usage
+
+### Basic Timing
+
+```php
+require __DIR__ . '/vendor/autoload.php';
+
+use SebastianBergmann\Timer\Timer;
+
+$timer = new Timer;
+
+$timer->start();
+
+foreach (\range(0, 100000) as $i) {
+    // ...
+}
+
+$duration = $timer->stop();
+
+var_dump(get_class($duration));
+var_dump($duration->asString());
+var_dump($duration->asSeconds());
+var_dump($duration->asMilliseconds());
+var_dump($duration->asMicroseconds());
+var_dump($duration->asNanoseconds());
+```
+
+The code above yields the output below:
+
+```
+string(32) "SebastianBergmann\Timer\Duration"
+string(9) "00:00.002"
+float(0.002851062)
+float(2.851062)
+float(2851.062)
+int(2851062)
+```
+
+### Resource Consumption
+
+#### Explicit duration
+
+```php
+require __DIR__ . '/vendor/autoload.php';
+
+use SebastianBergmann\Timer\ResourceUsageFormatter;
+use SebastianBergmann\Timer\Timer;
+
+$timer = new Timer;
+$timer->start();
+
+foreach (\range(0, 100000) as $i) {
+    // ...
+}
+
+print (new ResourceUsageFormatter)->resourceUsage($timer->stop());
+```
+
+The code above yields the output below:
+
+```
+Time: 00:00.002, Memory: 6.00 MB
+```
+
+#### Duration since PHP Startup (using unreliable `$_SERVER['REQUEST_TIME_FLOAT']`)
+
+```php
+require __DIR__ . '/vendor/autoload.php';
+
+use SebastianBergmann\Timer\ResourceUsageFormatter;
+
+foreach (\range(0, 100000) as $i) {
+    // ...
+}
+
+print (new ResourceUsageFormatter)->resourceUsageSinceStartOfRequest();
+```
+
+The code above yields the output below:
+
+```
+Time: 00:00.002, Memory: 6.00 MB
+```