[fix] add methodOverride to default configs

[geoffrich]

Fixes #3385

The svelte.config.js files in the templates were not being used and were overridden by the configs in /shared/+typescript and /shared/-typescript. This PR adds configs for the four cases (outlined below) and makes a note in the template configs that they are overridden.

• default + typescript: config with methodOverrides
• default - typescript: config with preprocess and methodOverrides
• skeleton + typescript: config with preprocess
• skeleton - typescript: default config

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[changeset-bot]

🦋 Changeset detected

Latest commit: 368bc75

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[Rich-Harris]

whoops! good catch