feat: update implementation of RSS feeds

Adds a new filter `convertRelativeLinks` that converts any relative link
to an absolute path
Adds an XML transform to minify the final output for smaller filesizes
Updates some data in meta
Adds a new macro for generating an RSS feed

src/pages/feeds/all.njk

@@ -1,27 +1,15 @@
 ---
 permalink: /feeds/all.xml
 layout: null
+filterTag:
+    - post
+    - game
+    - tv
+    - movie
+    - book
 eleventyExcludeFromCollections: true
 excludeFromSitemap: true
----<?xml version="1.0" encoding="utf-8"?>
-<feed xmlns="http://www.w3.org/2005/Atom">
-<title>{{ meta.siteName }}</title>
-<subtitle>{{ meta.siteDescription }}</subtitle>
-<link href="{{ meta.url }}/feeds/all.xml" rel="self" />
-<link href="{{ meta.url }}/" rel="alternate" type="text/html" />
-<id>{{ meta.url }}/</id>
-<author>
-<name>{{ meta.author }}</name>
-</author>
-{% for item in collections.all | filterByTags(["page"]) %}
-    <entry>
-    <id>{{ meta.url }}{{ item.url }}</id>
-    <title>{{ item.data.title | escape }}</title>
-    <link href="{{ item.url }}{{ post.url }}" />
-    <pubDate>{{ item.date }}</pubDate>
-    {# The first tag is always a type e.g. post, page, etc. #}
-    {%- for tag in item.data.tags %}{% if not loop.first %}<category term="{{ tag }}" />{% endif %}{%- endfor %}
-        <content type="html">{{ item.content | escape }}</content>
-        </entry>
-    {% endfor %}
-    </feed>
+---
+{% set data = collections.all | filterByTags(["page", "podcast"]) %}
+{% from "macros/feed.njk" import feed %}
+{{ feed(meta, data, page.date, permalink, title, filterTag) }}