fix(internal, cli-utils): Remove `null` cases from schema loaders, simplifying error handling

[kitten]

Summary

When applied, this change removes null cases from the schema loaders and replaces them with appropriate errors. Instead of having to handle missing schemas separately, the CLI now receives errors for each case where we previously fell back to returning a null result.

Set of changes

• Remove null cases from SDL loader
• Remove null case from URL loader
• Update types
• Update commands using schema loaders to remove null cases
• Retry with NODE_TLS_REJECT_UNAUTHORIZED disabled to prevent TLS errors
  • We assume CA certificates are trusted in this case, and that it's the user's responsibility to define a URL that is “safe” to access for GraphQL requests. Since we rely on API-side info and no code is executed this should be fine.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 17413451f4e8d4c34dc7e95241bd92805596849e

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

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