Multiplatform file resources (e.g read text/binary file)

[avdyushin]

Is your feature request related to a problem? Please describe.
Very often (especially in unit tests) we need a big data samples to use (now it's in code as byte arrays).
It's good to have access to them from common code (including common tests).

As a first version we can do read-only mode.

Not sure if it belongs resources module or brand new separate one.

Describe the solution you'd like

Some ideas over interface:

sealed class FilePath(val path: String) 

expect class FileResource(
    path: FilePath
) {
    fun open()
    fun nextLine(): String?
    fun nextByte(): Byte?
    fun close()
}

private fun FileResource.lineSequence() = Sequence {
    iterator {
        while (true) {
            nextLine()?.let { yield(it) } ?: break
        }
    }
}

fun <T> FileResource.useLines(block: (Sequence<String>) -> T): T {
    open()
    return block(lineSequence()).also { close() }
}

Where FilePath will wrap/maintain path for platform(Android,iOS,Native) and location (commonMain/resources, commonTest/resource, etc)

Do I can easily use it like this:

FileResource(path).useLines { string ->
   // use next string from file
}

Similar way can be implemented to access single Byte (by having byte iterator)

JVM

And Android as well:

actual class FileResource actual constructor(path: FilePath) {

    private val file = File(path.path)
    private lateinit var iterator: Iterator<String>

    actual fun open() {
        iterator = file.readLines().iterator()
    }

    actual fun nextLine(): String? {
        if (!iterator.hasNext()) return null
        return iterator.next()
    }

    actual fun close() {
    }
}

Native

Probably can be used in darwinMain:

actual class FileResource actual constructor(private val path: FilePath) {

    private var file: CPointer<FILE>? = null

    actual fun open() {
        file = fopen(__filename = path.path, __mode = "r")
        ?: throw NullPointerException("Can't open file at path: <${path.path}>")
    }

    actual fun nextLine() = memScoped {
        val buffer: CPointer<ByteVar> = allocArray(MAX_BUFFER_SIZE)
        fgets(buffer, MAX_BUFFER_SIZE, file)?.toKString()?.trimEnd() // remove newline
    }

    actual fun close() {
        fclose(file)
    }
}

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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