feat(migrate): add package handling

espanso-migrate/test/base/expected/match/packages/foo/custom.yml

@@ -0,0 +1,3 @@
+matches:
+  - trigger: "custom"
+    replace: "match"

espanso-migrate/test/base/expected/match/packages/foo/package.yml

@@ -0,0 +1,3 @@
+matches:
+  - trigger: "package_foo"
+    replace: "package_bar"

espanso-migrate/test/base/legacy/packages/foo/README.md

@@ -0,0 +1,9 @@
+---
+package_name: "foo"
+package_title: "Foo"
+package_desc: "Foo package"
+package_version: "0.1.0"
+package_author: "Federico Terzi"
+package_repo: "https://github.com/federico-terzi/espanso-hub-core"
+---
+Test package

espanso-migrate/test/base/legacy/packages/foo/custom.yml

@@ -0,0 +1,6 @@
+name: foo
+parent: default
+
+matches:
+  - trigger: "custom"
+    replace: "match"

espanso-migrate/test/base/legacy/packages/foo/package.yml

@@ -0,0 +1,6 @@
+name: foo
+parent: default
+
+matches:
+  - trigger: "package_foo"
+    replace: "package_bar"