add wasmtime 0.28.0 to ci

[plicease]

• the wasmtime.h file has been broken out into several files now in the wasmtime directory so diff'ing the header directory is not helpful
• there are a bunch of symbols that were added and removed

0.27.0:
  - wasi_instance_bind_import
  - wasi_instance_delete
  - wasi_instance_new
  - wasm_externtype_as_instancetype
  - wasm_externtype_as_instancetype_const
  - wasm_externtype_as_moduletype
  - wasm_externtype_as_moduletype_const
  - wasm_instance_type
  - wasm_instancetype_as_externtype
  - wasm_instancetype_as_externtype_const
  - wasm_instancetype_copy
  - wasm_instancetype_delete
  - wasm_instancetype_exports
  - wasm_instancetype_vec_copy
  - wasm_instancetype_vec_delete
  - wasm_instancetype_vec_new
  - wasm_instancetype_vec_new_empty
  - wasm_instancetype_vec_new_uninitialized
  - wasm_module_type
  - wasm_moduletype_as_externtype
  - wasm_moduletype_as_externtype_const
  - wasm_moduletype_copy
  - wasm_moduletype_delete
  - wasm_moduletype_exports
  - wasm_moduletype_imports
  - wasm_moduletype_vec_copy
  - wasm_moduletype_vec_delete
  - wasm_moduletype_vec_new
  - wasm_moduletype_vec_new_empty
  - wasm_moduletype_vec_new_uninitialized
  - wasmtime_externref_new_with_finalizer
  - wasmtime_func_as_funcref
  - wasmtime_func_new_with_env
  - wasmtime_funcref_as_func
  - wasmtime_funcref_table_get
  - wasmtime_funcref_table_grow
  - wasmtime_funcref_table_new
  - wasmtime_funcref_table_set
  - wasmtime_linker_get_one_by_name
  - wasmtime_store_add_fuel
  - wasmtime_store_fuel_consumed
  - wasmtime_store_gc
0.28.0:
  - wasm_foreign_as_ref
  - wasm_foreign_as_ref_const
  - wasm_foreign_copy
  - wasm_foreign_delete
  - wasm_foreign_get_host_info
  - wasm_foreign_new
  - wasm_foreign_same
  - wasm_foreign_set_host_info
  - wasm_foreign_set_host_info_with_finalizer
  - wasm_frame_copy
  - wasm_func_as_extern_const
  - wasm_global_as_extern_const
  - wasm_memory_as_extern_const
  - wasm_ref_as_extern
  - wasm_ref_as_extern_const
  - wasm_ref_as_foreign
  - wasm_ref_as_foreign_const
  - wasm_ref_as_func
  - wasm_ref_as_func_const
  - wasm_ref_as_global
  - wasm_ref_as_global_const
  - wasm_ref_as_instance
  - wasm_ref_as_instance_const
  - wasm_ref_as_memory
  - wasm_ref_as_memory_const
  - wasm_ref_as_module
  - wasm_ref_as_module_const
  - wasm_ref_as_table
  - wasm_ref_as_table_const
  - wasm_ref_as_trap
  - wasm_ref_as_trap_const
  - wasm_table_as_extern_const
  - wasmtime_caller_context
  - wasmtime_context_add_fuel
  - wasmtime_context_fuel_consumed
  - wasmtime_context_gc
  - wasmtime_context_get_data
  - wasmtime_context_set_data
  - wasmtime_context_set_wasi
  - wasmtime_extern_delete
  - wasmtime_extern_type
  - wasmtime_externref_clone
  - wasmtime_externref_delete
  - wasmtime_externtype_as_instancetype
  - wasmtime_externtype_as_moduletype
  - wasmtime_func_type
  - wasmtime_global_get
  - wasmtime_global_type
  - wasmtime_instance_export_get
  - wasmtime_instance_export_nth
  - wasmtime_instance_type
  - wasmtime_instancetype_as_externtype
  - wasmtime_instancetype_copy
  - wasmtime_instancetype_delete
  - wasmtime_instancetype_exports
  - wasmtime_linker_get
  - wasmtime_memory_data
  - wasmtime_memory_data_size
  - wasmtime_memory_grow
  - wasmtime_memory_new
  - wasmtime_memory_size
  - wasmtime_memory_type
  - wasmtime_module_clone
  - wasmtime_module_delete
  - wasmtime_module_type
  - wasmtime_moduletype_as_externtype
  - wasmtime_moduletype_copy
  - wasmtime_moduletype_delete
  - wasmtime_moduletype_exports
  - wasmtime_moduletype_imports
  - wasmtime_store_context
  - wasmtime_store_delete
  - wasmtime_store_new
  - wasmtime_table_get
  - wasmtime_table_grow
  - wasmtime_table_new
  - wasmtime_table_set
  - wasmtime_table_size
  - wasmtime_table_type
  - wasmtime_trap_new
  - wasmtime_val_copy
  - wasmtime_val_delete

• Wasm::Wasmtime::ModuleType should stringify in the same manner as Wasm::Wasmtime::Module

[plicease]

I think the place to start is to revisit the store class. It now has a context class that lives along side it, so getting the context should keep the store around until the context also falls out of scope. The WasiConfig now gets put into the context instead of a WasiInstance which has gone away. In the last commit I removed the gc method from store, but we can add it back as a compatibility layer calling gc on the context instead. The $store->gc should probably warn if called, telling the user to use the context version instead.

WasiInstance should maybe throw an exception if there is an attempt to instantiate it in 0.28, and code that is currently using it can be re-written to use $store->context instead