Fix issue with internal classes in SDK

[jplewa]

Task

Resolves: #41

Description

I changed three constructors in abstract classes from internal to protected (all resources in our provider SDKs inherit from these classes, so the constructors have to be available to them). I also changed the opts method in resources from this:

  public suspend fun opts(block: suspend CustomResourceOptionsBuilder.() -> Unit) {
    val builder = CustomResourceOptionsBuilder()
    block(builder)
    this.opts = builder.build()
  }

to this:

  public suspend fun opts(block: suspend CustomResourceOptionsBuilder.() -> Unit) {
    this.opts = com.pulumi.kotlin.options.opts(block)
  }

I also had to change the modifier of the underlying javaResource in resources to protected, because otherwise there were problems in subclasses, but that caused issues with the Alias class, so I added another property (underLyingJavaResource) that's exposed only as internal (it's also used in tests).

[myhau]

...
also changed the opts method in resources from this:

  public suspend fun opts(block: suspend CustomResourceOptionsBuilder.() -> Unit) {
    val builder = CustomResourceOptionsBuilder()
    block(builder)
    this.opts = builder.build()
  }

...

Is this done to prevent making the build method public?

[jplewa]

...
also changed the opts method in resources from this:

  public suspend fun opts(block: suspend CustomResourceOptionsBuilder.() -> Unit) {
    val builder = CustomResourceOptionsBuilder()
    block(builder)
    this.opts = builder.build()
  }

...

Is this done to prevent making the build method public?

Yes