[mlir] Fix bytecode reading of resource sections

This partially reverts #66380. The assertion that the underlying buffer
of an EncodingReader is aligned to any required alignments for resource
sections. Resources know their own alignment and pad their buffers
accordingly, but the bytecode reader doesn't know that ahead of time.
Consequently, it cannot give the resource EncodingReader a base buffer
aligned to the maximum required alignment.

A simple example from the test fails without this:

```mlir
module @TestDialectResources attributes {
  bytecode.test = dense_resource<resource> : tensor<4xi32>
} {}
{-#
  dialect_resources: {
    builtin: {
      resource: "0x2000000001000000020000000300000004000000",
      resource_2: "0x2000000001000000020000000300000004000000"
    }
  }
```