The overloads accepting a string will be deprecated soon, similar to
other functions in TargetRegistry.

Avoids more Triple->string->Triple round trip. This
is a continuation of f137c3d592e96330e450a8fd63ef7e8877fc1908

We already bump to COV6 by default in the front-end and backend. This PR
is for MLIR.

Note that COV6 requires ROCm 6.3+.

This change allows to expose through an interface attributes wrapping
content as external resources, and the usage inside the ModuleToObject
show how we will be able to provide runtime libraries without relying on
the filesystem.

This PR adds ability to pass non-default value to
`.amdhsa_code_object_version` metadata when serializing ROCDL GPU
modules.

It also fixes typos in two places.

---------

Co-authored-by: Fabian Mora <fmora.dev@gmail.com>

This patch adds the `#gpu.kernel_metadata` and `#gpu.kernel_table`
attributes. The `#gpu.kernel_metadata` attribute allows storing metadata
related to a compiled kernel, for example, the number of scalar
registers used by the kernel. The attribute only has 2 required
parameters, the name and function type. It also has 2 optional
parameters, the arguments attributes and generic dictionary for storing
all other metadata.

The `#gpu.kernel_table` stores a table of `#gpu.kernel_metadata`,
mapping the name of the kernel to the metadata.

Finally, the function `ROCDL::getAMDHSAKernelsELFMetadata` was added to
collect ELF metadata from a binary, and to test the class methods in
both attributes.

Example:
```mlir
gpu.binary @binary [#gpu.object<#rocdl.target<chip = "gfx900">, kernels = #gpu.kernel_table<[
    #gpu.kernel_metadata<"kernel0", (i32) -> (), metadata = {sgpr_count = 255}>,
    #gpu.kernel_metadata<"kernel1", (i32, f32) -> (), arg_attrs = [{llvm.read_only}, {}]>
  ]> , bin = "BLOB">]

```
The motivation behind these attributes is to provide useful information
for things like tunning.

---------

Co-authored-by: Mehdi Amini <joker.eph@gmail.com>

This patch adds an argument to `gpu::TargetAttrInterface::createObject`
to pass the GPU module. This is useful as `gpu::ObjectAttr` contains a
property dict for metadata, hence the module can be used for extracting
things like the symbol table and adding it to the property dict.

---------

Co-authored-by: Oleksandr "Alex" Zinenko <ftynse@gmail.com>

This patch constructs the AMDGCN ISA control variable explicitly instead
of linking against the library shipped with ROCm. This change prevents
issues arising from the order in which the AMDGCN libraries are linked.

Reland: https://github.com/llvm/llvm-project/pull/95456

This patch improves the ROCDL gpu serialization API by:
- Introducing the enum `AMDGCNLibraries` for specifying the AMD GCN
device code libraries to use during linking.
- Removing `getCommonBitcodeLibs` in favor of `AMDGCNLibraries`.
Previously `getCommonBitcodeLibs` would try to load all AMD GCN bitcode
librariesm now it will only load the requested libraries.
- Exposing the `compileToBinary` method and making it virtual, allowing
downstream users to re-use this method.
- Exposing `moduleToObjectImpl`, this method provides a prototype flow
for compiling to binary, allowing downstream users to re-use this
method.
- It also avoids constructing the control variables if no device
libraries are being used.
- Changes the style of the error messages to be composable, ie no full
stops.
- Adds an error message for when the ROCm toolkit can't be found but it
was required.