[event-engine] Separate promise context from default event engine hea…

…ders (#36148)

These two things are different (event engine being a context has nothing to do with the ability to get a default event engine).

Lumping them into the same header means that things that want the context also need to want the default event engine declarations, which in turn pull in CoreConfiguration -- which ultimately means that nothing that is depended on by CoreConfiguration can consume the event engine context, which is undesirable (and causing dependency loops in current work).

Also includes an impressive number of cleanups to `grpc_base` because I ran `fix_build_deps` on that target as part of this.

Closes #36148

COPYBARA_INTEGRATE_REVIEW=#36148 from ctiller:context-isnt-default--default-isnt-context a4fdad9
PiperOrigin-RevId: 617961015

BUILD

@@ -1962,20 +1962,15 @@ grpc_cc_library(
     }),
     external_deps = [
         "absl/base:core_headers",
-        "absl/cleanup",
         "absl/container:flat_hash_map",
-        "absl/container:flat_hash_set",
         "absl/container:inlined_vector",
         "absl/functional:any_invocable",
         "absl/functional:function_ref",
-        "absl/hash",
         "absl/meta:type_traits",
-        "absl/random",
         "absl/status",
         "absl/status:statusor",
         "absl/strings",
         "absl/strings:str_format",
-        "absl/time",
         "absl/types:optional",
         "absl/utility",
         "madler_zlib",
@@ -1989,7 +1984,6 @@ grpc_cc_library(
     visibility = ["@grpc:alt_grpc_base_legacy"],
     deps = [
         "api_trace",
-        "byte_buffer",
         "call_combiner",
         "call_trace",
         "call_tracer",
@@ -1998,43 +1992,31 @@ grpc_cc_library(
         "channel_stack_builder",
         "channelz",
         "config",
-        "config_vars",
         "cpp_impl_of",
         "debug_location",
-        "dynamic_annotations",
         "exec_ctx",
         "gpr",
         "grpc_public_hdrs",
         "grpc_trace",
         "iomgr",
-        "iomgr_buffer_list",
-        "iomgr_internal_errqueue",
         "iomgr_timer",
         "legacy_context",
         "orphanable",
-        "parse_address",
         "promise",
         "ref_counted_ptr",
-        "resource_quota_api",
-        "sockaddr_utils",
         "stats",
-        "tcp_tracer",
-        "uri_parser",
         "//src/core:1999",
         "//src/core:activity",
         "//src/core:all_ok",
         "//src/core:arena",
         "//src/core:arena_promise",
         "//src/core:atomic_utils",
         "//src/core:bitset",
-        "//src/core:call_factory",
         "//src/core:call_filters",
         "//src/core:call_final_info",
         "//src/core:call_finalization",
         "//src/core:call_spine",
-        "//src/core:cancel_callback",
         "//src/core:channel_args",
-        "//src/core:channel_args_endpoint_config",
         "//src/core:channel_args_preconditioning",
         "//src/core:channel_fwd",
         "//src/core:channel_init",
@@ -2043,75 +2025,47 @@ grpc_cc_library(
         "//src/core:closure",
         "//src/core:compression",
         "//src/core:connectivity_state",
-        "//src/core:construct_destruct",
         "//src/core:context",
         "//src/core:default_event_engine",
-        "//src/core:dual_ref_counted",
         "//src/core:error",
         "//src/core:error_utils",
         "//src/core:event_engine_common",
-        "//src/core:event_engine_extensions",
-        "//src/core:event_engine_memory_allocator_factory",
-        "//src/core:event_engine_query_extensions",
-        "//src/core:event_engine_shim",
-        "//src/core:event_engine_tcp_socket_utils",
-        "//src/core:event_engine_trace",
-        "//src/core:event_log",
+        "//src/core:event_engine_context",
         "//src/core:experiments",
         "//src/core:for_each",
         "//src/core:gpr_atm",
         "//src/core:gpr_manual_constructor",
         "//src/core:gpr_spinlock",
-        "//src/core:grpc_sockaddr",
         "//src/core:if",
-        "//src/core:init_internally",
         "//src/core:iomgr_fwd",
-        "//src/core:iomgr_port",
-        "//src/core:json",
-        "//src/core:json_writer",
         "//src/core:latch",
         "//src/core:loop",
         "//src/core:map",
         "//src/core:match",
-        "//src/core:memory_quota",
         "//src/core:message",
         "//src/core:metadata",
         "//src/core:metadata_batch",
         "//src/core:metrics",
         "//src/core:no_destruct",
-        "//src/core:per_cpu",
         "//src/core:pipe",
         "//src/core:poll",
-        "//src/core:pollset_set",
-        "//src/core:posix_event_engine_base_hdrs",
-        "//src/core:posix_event_engine_endpoint",
         "//src/core:promise_status",
         "//src/core:promise_trace",
         "//src/core:race",
-        "//src/core:random_early_detection",
         "//src/core:ref_counted",
-        "//src/core:resolved_address",
-        "//src/core:resource_quota",
-        "//src/core:resource_quota_trace",
         "//src/core:seq",
         "//src/core:server_interface",
         "//src/core:slice",
         "//src/core:slice_buffer",
         "//src/core:slice_cast",
         "//src/core:slice_refcount",
-        "//src/core:socket_mutator",
         "//src/core:stats_data",
         "//src/core:status_flag",
         "//src/core:status_helper",
-        "//src/core:strerror",
-        "//src/core:thread_quota",
         "//src/core:time",
         "//src/core:transport_fwd",
-        "//src/core:try_join",
         "//src/core:try_seq",
         "//src/core:useful",
-        "//src/core:windows_event_engine",
-        "//src/core:windows_event_engine_listener",
     ],
 )