Add tt coredump (#3139)

Resolves #3000

Author: p7nov

doc/reference/tt_cli/commands.rst

@@ -38,6 +38,8 @@ help for the given command.
             -   Print the contents of ``.snap`` or ``.xlog`` files into stdout
         *   -   :doc:`play <play>`
             -   Play the contents of ``.snap`` or ``.xlog`` files to another Tarantool instance
+        *   -   :doc:`coredump <coredump>`
+            -   Manipulate Tarantool core dumps
 
 ..  toctree::
     :hidden:
@@ -54,4 +56,5 @@ help for the given command.
     connect <connect>
     rocks <rocks>
     cat <cat>
-    play <play>
+    play <play>
+    coredump <coredump>

doc/reference/tt_cli/coredump.rst

@@ -0,0 +1,73 @@
+.. _tt-coredump:
+
+Manipulating Tarantool core dumps
+=================================
+
+..  code-block:: bash
+
+    tt coredump COMMAND [ARGUMENT]
+
+``tt coredump`` provides commands for manipulating Tarantool core dumps.
+
+..  note::
+
+        ``tt coredump`` does not support macOS.
+
+Commands
+--------
+
+..  container:: table
+
+    ..  list-table::
+        :widths: 20 80
+        :header-rows: 0
+
+        *   -   ``pack``
+            -   Pack a Tarantool core dump and supporting data into a ``tar.gz`` archive
+        *   -   ``unpack``
+            -   Unpack a Tarantool core dump archive
+        *   -   ``inspect``
+            -   Inspect a Tarantool core dump directory with the
+                `GNU debugger <https://www.sourceware.org/gdb/>`__ (``gdb``)
+
+
+Details
+-------
+
+To be able to investigate Tarantool crashes, make sure that core dumps are enabled
+on the host. Here is the :ref:`instruction on enabling core dumps on Unix systems <admin-core_dumps>`.
+
+``tt coredump pack`` packs the given core dump together with files and data
+that can help the crash investigation. This includes:
+
+*   Tarantool executable
+*   Tarantool version information
+*   OS information
+*   Shared libraries
+
+``tt coredump inspect`` requires ``gdb`` installed on the host.
+The directory being inspected must have the same structure as the core dump archive
+created by ``tt coredump pack``.
+
+Examples
+--------
+
+*   Pack a ``tar.gz`` file with a Tarantool core dump and supporting data:
+
+    ..  code-block:: bash
+
+        tt coredump pack name.core
+
+
+*   Unpack a ``tar.gz`` archive packed by ``tt coredump pack``:
+
+    ..  code-block:: bash
+
+        tt coredump unpack tarantool-core-dump.tar.gz
+
+
+*   Inspect the unpacked core dump with ``gdb``:
+
+    ..  code-block:: bash
+
+        tt coredump inspect tarantool-core-dump