#25462 fix(typescript-...): Fix basic auth without username or password

Missing password or username in multiple typescript generators concat the undefined to the string resulting in a invalid auth header.

typescript-inversify also misses a 'Basic ' prefix

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Summary by cubic

Fixes basic auth in TypeScript and JavaScript generators so a missing username or password no longer produces an invalid Authorization header, and restores the missing Basic prefix in the typescript-inversify generator.

• Defaults missing username or password values to empty strings instead of concatenating undefined.
• Updates Javascript-Apollo, Javascript-Flowtyped, the Javascript apollo library, typescript-angular, typescript-fetch, typescript-inversify, typescript-jquery, typescript-nestjs, and typescript-playwright templates, and regenerates affected samples.