Handle invalid remote contract schemas

[dmerand]

WHY are these changes introduced?

A malformed or invalid remote contract JSON Schema served by the platform must not abort CLI commands.

WHAT is this pull request doing?

• Fall back to merged.parseConfigurationObject unchanged when the remote schema cannot normalize or compile.
• Omit a remote-only specification only when its schema cannot normalize. getArrayRejectingUndefined removes the resulting undefined; valid remote-only specifications remain.
• Warn once per parser instance or specification fetch. app dev reloads reuse app.specifications, so reloads do not warn again. A new CLI invocation can warn again.
• Keep server-side validation authoritative.

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