[objects] Add shared-function-info.cc

.. and move all SharedFunctionInfo implementations from objects.cc to
the dedicated shared-function-info.cc.

Drive-by: Also move remaining JSRegExp impls.

Bug: v8:8888
Change-Id: I59adc3928f379eeb8b70f26d7e51d01c889c9a47
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2292240
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68832}

BUILD.gn

@@ -1035,6 +1035,7 @@ action("postmortem-metadata") {
     "src/objects/scope-info.h",
     "src/objects/script.h",
     "src/objects/script-inl.h",
+    "src/objects/shared-function-info.cc",
     "src/objects/shared-function-info.h",
     "src/objects/shared-function-info-inl.h",
     "src/objects/string.cc",
@@ -2898,6 +2899,7 @@ v8_source_set("v8_base_without_compiler") {
     "src/objects/script-inl.h",
     "src/objects/script.h",
     "src/objects/shared-function-info-inl.h",
+    "src/objects/shared-function-info.cc",
     "src/objects/shared-function-info.h",
     "src/objects/slots-atomic-inl.h",
     "src/objects/slots-inl.h",