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/symfony/mime/CHANGELOG.md

@@ -0,0 +1,50 @@
+CHANGELOG
+=========
+
+6.3
+---
+
+ * Support detection of related parts if `Content-Id` is used instead of the name
+ * Add `TextPart::getDisposition()`
+
+6.2
+---
+
+ * Add `File`
+ * Deprecate `Email::attachPart()`, use `addPart()` instead
+ * Deprecate calling `Message::setBody()` without arguments
+
+6.1
+---
+
+ * Add `DataPart::getFilename()` and `DataPart::getContentType()`
+
+6.0
+---
+
+ * Remove `Address::fromString()`, use `Address::create()` instead
+ * Remove `Serializable` interface from `RawMessage`
+
+5.2.0
+-----
+
+ * Add support for DKIM
+ * Deprecated `Address::fromString()`, use `Address::create()` instead
+
+4.4.0
+-----
+
+ * [BC BREAK] Removed `NamedAddress` (`Address` now supports a name)
+ * Added PHPUnit constraints
+ * Added `AbstractPart::asDebugString()`
+ * Added `Address::fromString()`
+
+4.3.3
+-----
+
+ * [BC BREAK] Renamed method `Headers::getAll()` to `Headers::all()`.
+
+4.3.0
+-----
+
+ * Introduced the component as experimental