Support migrating subscription link extension

[AniTumany]

WHY are these changes introduced?

Closes: https://github.com/Shopify/subscriptions-app-remix/issues/2062
Rebased off of: #4758
Should be merged after: #4787

WHAT is this pull request doing?

Supports migrating dashboard-managed subscription link extensions to become CLI managed as part of the dev and deploy commands.

How to test your changes?

Follow the steps described in #4787 to import subscription link extensions to CLI. Once imported run shopify app dev or shopify app deploy to migrate the extension to be CLI managed.

Post-release steps

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/public/node/themes/api.d.ts

@@ -5,7 +5,7 @@ export type AssetParams = Pick<ThemeAsset, 'key'> & Partial<Pick<ThemeAsset, 'va
 export declare function fetchTheme(id: number, session: AdminSession): Promise<Theme | undefined>;
 export declare function fetchThemes(session: AdminSession): Promise<Theme[]>;
 export declare function createTheme(params: ThemeParams, session: AdminSession): Promise<Theme | undefined>;
-export declare function fetchThemeAssets(id: number, filenames: Key[], session: AdminSession): Promise<ThemeAsset[]>;
+export declare function fetchThemeAsset(id: number, key: Key, session: AdminSession): Promise<ThemeAsset | undefined>;
 export declare function deleteThemeAsset(id: number, key: Key, session: AdminSession): Promise<boolean>;
 export declare function bulkUploadThemeAssets(id: number, assets: AssetParams[], session: AdminSession): Promise<Result[]>;
 export declare function fetchChecksums(id: number, session: AdminSession): Promise<Checksum[]>;

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	71.76% (-0.29% 🔻)	8445/11768
🟡	Branches	68.24% (-0.25% 🔻)	4093/5998
🟡	Functions	71.31% (-0.02% 🔻)	2217/3109
🟡	Lines	72.2% (-0.23% 🔻)	7985/11059

Show new covered files 🐣

St.❔	File	Statements	Branches	Functions	Lines
🔴	... / clear.ts	0%	100%	0%	0%
🔴	... / generate.ts	0%	100%	0%	0%
🔴	... / list.ts	0%	100%	0%	0%
🔴	... / notifications.ts	0%	0%	0%	0%
🟢	... / global-context.ts	100%	100%	100%	100%
🟡	... / notifications-system.ts	61.29%	60.32%	84.21%	68.83%

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / app.ts	85.92% (-0.22% 🔻)	70.37% (+0.24% 🔼)	91.67% (+0.18% 🔼)	87.8% (+0.3% 🔼)
🟢	... / identifiers-extensions.ts	79.49% (-5.27% 🔻)	71.43% (-3.15% 🔻)	100%	80.95% (-5.22% 🔻)
🟢	... / conf-store.ts	100%	90.48% (-2.21% 🔻)	100%	100%
🟢	... / ConcurrentOutput.tsx	98.39% (-1.61% 🔻)	90.91% (-4.55% 🔻)	100%	98.33% (-1.67% 🔻)
🟢	... / base-command.ts	84.81% (+0.39% 🔼)	80% (-1.25% 🔻)	77.27%	85.51% (+0.43% 🔼)
🔴	... / cli.ts	1.39% (-0.02% 🔻)	0%	0%	1.54% (-0.02% 🔻)

Test suite run success

1914 tests passing in 870 suites.

Report generated by 🧪jest coverage report action from 574019d

[github-actions]

We detected some changes at packages/*/src and there are no updates in the .changeset.
If the changes are user-facing, run "pnpm changeset add" to track your changes and include them in the next release CHANGELOG.