Adding dynamic_theme and gemini_tasks (#2287)

Adds two new samples that use the Google Generative AI SDK for Dart.
Both were created by @rodydavis. I'm merely the uploader so to speak.

## Pre-launch Checklist

- [X] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [X] I signed the [CLA].
- [X] I read the [Contributors Guide].
- [X] I updated/added relevant documentation (doc comments with `///`).
- [X] All existing and new tests are passing.

tool/flutter_ci_script_beta.sh

@@ -26,6 +26,8 @@ declare -ar PROJECT_NAMES=(
     "deeplink_store_example"
     "desktop_photo_search/fluent_ui"
     "desktop_photo_search/material"
+    # TODO: 'surfaceVariant' is deprecated and shouldn't be used.
+    # "dynamic_theme"
     "experimental/federated_plugin/federated_plugin"
     "experimental/federated_plugin/federated_plugin/example"
     "experimental/federated_plugin/federated_plugin_macos"
@@ -44,6 +46,8 @@ declare -ar PROJECT_NAMES=(
     "form_app"
     # TODO: 'onBackground' is deprecated and shouldn't be used.
     # "game_template"
+    # TODO: 'surfaceVariant' is deprecated and shouldn't be used.
+    # "gemini_tasks"
     "google_maps"
     "infinite_list"
     "ios_app_clip"

tool/flutter_ci_script_master.sh

@@ -26,6 +26,8 @@ declare -ar PROJECT_NAMES=(
     "deeplink_store_example"
     "desktop_photo_search/fluent_ui"
     "desktop_photo_search/material"
+    # TODO: 'surfaceVariant' is deprecated and shouldn't be used.
+    # "dynamic_theme"
     "experimental/federated_plugin/federated_plugin"
     "experimental/federated_plugin/federated_plugin/example"
     "experimental/federated_plugin/federated_plugin_macos"
@@ -44,6 +46,8 @@ declare -ar PROJECT_NAMES=(
     "form_app"
     # TODO: 'onBackground' is deprecated and shouldn't be used.
     # "game_template"
+    # TODO: 'surfaceVariant' is deprecated and shouldn't be used.
+    # "gemini_tasks"
     "google_maps"
     "infinite_list"
     "ios_app_clip"

tool/flutter_ci_script_stable.sh

@@ -25,6 +25,7 @@ declare -ar PROJECT_NAMES=(
     "deeplink_store_example"
     "desktop_photo_search/fluent_ui"
     "desktop_photo_search/material"
+    "dynamic_theme"
     "experimental/federated_plugin/federated_plugin"
     "experimental/federated_plugin/federated_plugin/example"
     "experimental/federated_plugin/federated_plugin_macos"
@@ -39,6 +40,7 @@ declare -ar PROJECT_NAMES=(
     "flutter_maps_firestore"
     "form_app"
     "game_template"
+    "gemini_tasks"
     "google_maps"
     "infinite_list"
     "ios_app_clip"