[Bug][typescript-fetch] Fix missing close parenthesis in oneOf models.

[btpnlsl]

Fixes #21639

PR #21464 provided some changes to add serialization & deserialization logic for primitive and enum types used by the ToJSONTypes & FromJSONTyped methods of 'oneOf' models.

There are a couple of cases where the if-statements used in the ToJSONTyped methods generated by the template are missing closing parentheses, such as when serializing an Array, Array.

This PR fixes these cases and modifies the unit test for Issue 21295 to check for the correct number of closing parenthesis.

Just as a side note, having the unit test check for string literals is probably not a great long term strategy as the approach is brittle; changes in formatting which are technically correct can break these tests. It would probably be better to have a tool like assertj (which is used for the Java generation tests) or to use some sort of typescript linting tools to check the output of each test. I took a look at using typescript-eslint, but it seems that that tooling is dependent on running with npm.

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PR #21464 - @DavidGrath

[DavidGrath]

@btpnlsl , thanks for the fix

Just as a side note, having the unit test check for string literals is probably not a great long term strategy

#21414

[macjohnny]

thanks for the fix