[CK_TILE] Add gtests for FMHA (#2744)

* Improve random number generation

* use different seed for each input (Q, K, V...);
* use deterministic generation of:
  * seqstart_q/k (for group mode);
  * block_table (for paged-kvcahe);
  * cache_batch_idx (for kvcache);

* Extract arg_parser-related code from run functions to use them as tests

* Split examples into main programs and fmha runners, build instances separately

* Add dummy tests that use instances and runners

* Fix a missed corner case of f32->f8 conversion

When value if < min f8 denormal but > min f8 denormal / 2, it must be
rounded to min f8 denormal (i.e. 0b1), not to 0.

* Fix incorrect fp8 scales for P and O in validation code

DataTypeConfig was incorrectly compared with fp8_t.

* Add host generation of dropout random values and use it for validation

Previously host validation (reference_batched_dropout) used random
numbers generated by BlockDropout of the kernel, meaning that incorrect
generation on device (bad distribution, repeated numbers, too many zeros,
etc.) would not trigger any validation errors.

* Implement tests from smoke_test_bwd.sh

* Return result as enum to distinguish failure and missing instance

* Add tests for bwd features: bias, alibi, dropout

* Implement tests from smoke_test_fwd.sh

* Pass seqlen_q/k as vectors to fwd and bwd runners

* Add tests for fwd features: bias, alibi, dropout

* Add tests for pagedkv and splitkv

* Fix conditions when to use splitkv and pagedkv kernels

splitkv was executed only when use_kvcache which == (need_append_kvcache || use_cache_batch_idx || 0 < page_block_size).
In the SplitKV tests: the regular fwd kernel was executed if use_cache_batch_idx was not requested even when num_splitkv > 1.
In the AppendKV tests: the pagedkv kernel was executed but it often failed to find an instance.

* Add tests for appendkv

* Use is_v_rowmajor = true because there are no instances with column layout anymore

* Split public and private compile options for instances

Tests and examples need to know only about CK_TILE_FMHA_FWD_*_API.

* Improve parsing validation in bias and mask

* Pass bias as string for consistency with mask

* Catch parsing and other exceptions

* Add bwd test for deterministic flag

* Initialize fp8 tensors (-init=ufq) similarly to uf

* Fix splitkv/pagedkv invocation: use padded sk when seqlen_k_ptr is not null

seqlen_k cannot be used to determine padding when seqlen_k_ptr is
provided. The actual seqlen_k is taken from seqlen_k_ptr[b].
Even seqlen_k values (% bn0 == 0) use padded seqlen_k while seqlen_k_ptr
may contain arbitrary values.
In the example or tests this produces incorrect results with appendkv
(for example, -d=32 -s=1 -s_k=64 -s_knew=7 -vlayout=c -b=8).

* Fix use_pagedkv value when kvcache = true but page_block_size = 0

In this case block_table_ptr is nullptr which is accessed in the kernel.

* Clean up bwd tests

* Unify fwd tests for f16/bf16 and fp8

* Use better explicit instantiation declaration for fmha_bwd<2>

* Use the same seed for all tests, allow to override it with env variable

* Undo clang-format of one irrelevant file

For some reason my local clang-format-18 and the one in CI work differently.

* Do not build instances and tests on unsupported archs

* Build instance libraries as OBJECT library

* CI: Enable sccache for HIP

There are source files with LANGUAGE HIP, they need
-DCMAKE_HIP_COMPILER_LAUNCHER=sccache

* Add tests to REGRESSION_TESTS

* Fix OOB accesses in deterministic bwd due to incorrectly assumed kN0

The runner assumes kN0 = (hdim_q <= 128) ? 128 : 64 but there are
smaller tiles (for tr_load or fp32). This can create too small dq_acc_buf.

* Pass CK_TILE_FMHA_FWD_*_API as INTERFACE compile options

The instances don't actually depend on them, only examples and tests do.
Passing these definitions as INTERFACE allows to change FMHA_FWD_ENABLE_APIS
without recompiling instances that are already in ccache.

* Fix formatting and names

include/ck_tile/host.hpp

@@ -18,6 +18,7 @@
 #include "ck_tile/host/kernel_launch.hpp"
 #include "ck_tile/host/ranges.hpp"
 #include "ck_tile/host/reference/reference_batched_dropout.hpp"
+#include "ck_tile/host/reference/reference_batched_dropout_randval.hpp"
 #include "ck_tile/host/reference/reference_batched_elementwise.hpp"
 #include "ck_tile/host/reference/reference_batched_gemm.hpp"
 #include "ck_tile/host/reference/reference_batched_masking.hpp"