Don't mess with tsconfig

[kamilafsar]

We're adding things to the tsconfig (in memory, in order to compile), but we need to throw an error instead, and let the dev fix it.

https://github.com/samen-io/samen/blob/main/packages/server/src/commands/build.ts

https://github.com/samen-io/samen/blob/main/packages/server/src/commands/export.ts

https://github.com/samen-io/samen/blob/c9d559c3a452650e5773be25b1e53c02b232183e/packages/core/src/VirtualCompilerHost.ts#L13

https://github.com/samen-io/samen/blob/c9d559c3a452650e5773be25b1e53c02b232183e/packages/server/src/commands/serve/DevServerCompilerHost.ts#L15