upgrade to typescript 5.0 and use new decorator API

[lolopinto]

new decorator API created in https://devblogs.microsoft.com/typescript/announcing-typescript-5-0/#decorators

this involves breaking changes since API for gqlField et al have changed.

The API is still not perfect:

  @gqlField({
    nodeName: "User",
    type: GraphQLString,
    name: "fullName",
  })
  get fullName(): string {
    return this.firstName + " " + this.lastName;
  }

as we have to reference nodeName: 'User' in each gqlField definition which is annoying since the new decorator API provides less access to things than the previous one did.

Another big change is gqlArg is gone since parameter arguments aren't supported tc39/proposal-decorators#47

addresses #1392