Add autocast support for x86amx

[sayantn]

Builds on #140763 (well currently it just includes those commits as well) by further adding autocasts for x86amx from/to vectors of size 8192 bits.

This also disables SIMD vector abi checks for the "unadjusted" abi because

• This is primarily used to link with LLVM intrinsics, which don't actually lower to function calls with vector arguments. Even with other cg backends, this is true.
• This ABI is internal and perma-unstable (and also super specific), so it is very unlikely that this will cause breakages.
• (The primary reason) Without doing this we can't actually use 8192 bit long vectors to represent x86amx

This PR also does some refactoring in our intrinsic caching mechanism. The core philosophy of this is that the LLVM intrinsic is uniquely determined by its base name and its type parameters (this is only relevant if the intrinsic is not overloaded).

• Instead of caching based on the full name, we cache based on the base name and the type parameters. This helps with the implementations because often we do elaborate transformations to string representation from LLVM type to get the full overloaded LLVM name, which is no longer needed.
• This makes the caching more flexible. For overloaded intrinsics like llvm.is.constant, we could only ever manually cache a finite amount of types, but with this we can now dynamically generate the cache (which also has the byproduct that is_val_statically_known is now implemented in cg_llvm for all immediate types.

Just putting this as a PR to notify myself that this exists

[rust-log-analyzer]

The job mingw-check-2 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] rustc_index_macros test:true 0.153
error[E0308]: mismatched types
    --> compiler/rustc_codegen_llvm/src/builder.rs:1399:77
     |
1399 |             let pointer = self.call_intrinsic("llvm.threadlocal.address", &[global]);
     |                                                                             ^^^^^^ expected `&llvm::ffi::Type`, found `&llvm::ffi::Value`
     |
    ::: compiler/rustc_codegen_llvm/src/llvm/ffi.rs:746:5
     |
746  |     pub(crate) type Type;
     |     -------------------- the expected foreign type
---

error[E0061]: this method takes 3 arguments but 2 arguments were supplied
    --> compiler/rustc_codegen_llvm/src/builder.rs:1399:32
     |
1399 |             let pointer = self.call_intrinsic("llvm.threadlocal.address", &[global]);
     |                                ^^^^^^^^^^^^^^--------------------------------------- argument #3 of type `&[&llvm::ffi::Value]` is missing
     |
note: method defined here
    --> compiler/rustc_codegen_llvm/src/builder.rs:1553:19
     |
1553 |     pub(crate) fn call_intrinsic(
     |                   ^^^^^^^^^^^^^^
...
1557 |         args: &[&'ll Value],
     |         -------------------
help: provide the argument
     |
1399 |             let pointer = self.call_intrinsic("llvm.threadlocal.address", &[global], /* &[&llvm::ffi::Value] */);
     |                                                                                    ++++++++++++++++++++++++++++

error[E0308]: mismatched types
    --> compiler/rustc_codegen_llvm/src/builder.rs:1846:64
     |
1846 |             let cond = self.call_intrinsic("llvm.type.test", &[llfn, typeid]);
     |                                                                ^^^^ expected `&llvm::ffi::Type`, found `&llvm::ffi::Value`
     |
    ::: compiler/rustc_codegen_llvm/src/llvm/ffi.rs:746:5
     |
746  |     pub(crate) type Type;
     |     -------------------- the expected foreign type
---

error[E0061]: this method takes 3 arguments but 2 arguments were supplied
    --> compiler/rustc_codegen_llvm/src/builder.rs:1846:29
     |
1846 |             let cond = self.call_intrinsic("llvm.type.test", &[llfn, typeid]);
     |                             ^^^^^^^^^^^^^^----------------------------------- argument #3 of type `&[&llvm::ffi::Value]` is missing
     |
note: method defined here
    --> compiler/rustc_codegen_llvm/src/builder.rs:1553:19
     |
1553 |     pub(crate) fn call_intrinsic(
     |                   ^^^^^^^^^^^^^^
...
1557 |         args: &[&'ll Value],
     |         -------------------
help: provide the argument
     |
1846 |             let cond = self.call_intrinsic("llvm.type.test", &[llfn, typeid], /* &[&llvm::ffi::Value] */);
     |                                                                             ++++++++++++++++++++++++++++

Some errors have detailed explanations: E0061, E0308.
For more information about an error, try `rustc --explain E0061`.
[RUSTC-TIMING] rustc_codegen_llvm test:false 3.278

[sayantn]

I have decided to split this into different PRs - one for the intrinsic implementation changes, and the AMX changes I will merge with #140763