topics: add a config to reject draft changeset without topic on a server
This patch adds a new config option experimental.topic-mode.server which if
sets to True, the server won't accept any draft changeset without topic on it.
In case both `experimental.topic-mode.server` and
`experimental.topic.publish-bare-branch` are set to True, the enforce-topic one
is respected.
Tests are added for it. The CHANGELOG file is also updated mentioning about the
config option.
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Evolve Commands Reference
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.. highlight:: none
amend
-----
.. hghelp:: amend
evolve
------
.. hghelp:: evolve
fold
----
.. hghelp:: fold
metaedit
--------
.. hghelp:: metaedit
next
----
.. hghelp:: next
obslog
------
.. hghelp:: obslog
pdiff
-----
.. hghelp:: pdiff
previous
--------
.. hghelp:: previous
prune
-----
.. hghelp:: prune
pstatus
-------
.. hghelp:: pstatus
split
-----
.. hghelp:: split
touch
-----
.. hghelp:: touch
uncommit
--------
.. hghelp:: uncommit