fix(zod): parenthesize optional and multi-value literal types in schema text

[Mohammed Alkindi (MohammedAlkindi)]

getZodSchemaAsTypeScript emits optional types as T | undefined and multi-value literals as a union of their values, but gave both object precedence, so they lost their parentheses. On main:

z.array(z.literal(["a", "b"]))                     "a" | "b"[]
z.array(z.string().optional())                     string | undefined[]
z.intersection(z.string().optional(), z.literal(["a", "b"]))  string | undefined & "a" | "b"
z.tuple([z.string()]).rest(z.number().optional())  [string, ...number | undefined[]]
z.tuple([z.string(), z.literal(["a", "b"]).optional()])  [string, "a" | "b"?]

The last two are not valid TypeScript, and the others describe a different type than the schema. getTypePrecedence now gives both union precedence. Single-value literals are unchanged.

npm test in typescript/: 121 pass. Six of the eight new tests fail on main; the other two check that single literals and union members stay unparenthesized.