refactor: manifest迁移到ota/文件夹

- ota/manifest.json (stable)
- ota/manifest-beta.json
- ota/manifest-nightly.json
- MainActivity URL更新为ota/路径

ota/manifest-beta.json

@@ -0,0 +1 @@
+{"version":"0.1.0","builds":{"android":{"type":"apk","tag":"v0.1.0-dav-android-7","url":"https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk","sha256":"6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6","size":3223411,"channel":"beta"}}}

ota/manifest-nightly.json

@@ -0,0 +1 @@
+{"version":"0.1.0","builds":{"android":{"type":"apk","tag":"v0.1.0-dav-android-7","url":"https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk","sha256":"6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6","size":3223411,"channel":"nightly"}}}

ota/manifest.json

@@ -0,0 +1,14 @@
+{
+  "version": "0.1.0",
+  "builds": {
+    "android": {
+      "type": "apk",
+      "tag": "v0.1.0-dav-android-7",
+      "url": "https://git.childish-ghost.com/LukeMackin/Yuzu-GCA/releases/download/v0.1.0-dav-android-7/v0.1.0-dav-android-debug.apk",
+      "sha256": "6cd6bbfe07e8b86b06bc328b7b08138dfb00defc71c8bcc98fbb256b2153aba6",
+      "size": 3223411,
+      "channel": "stable",
+      "minVersion": "0.1.0"
+    }
+  }
+}