mercurial/templates/rss/changelogentry.tmpl

copies: introduce a basic Rust function for `combine_changeset_copies`

This new function mirror the python code.  This first implementation does a lot
of data copies and is therefore quite slow. However my goal here is to create a
simple "frame" from where to start adding optimization.

This patch focus on the `hg-core` part of this work. Coming patches will do the
necessary `hg-cpython` work  to be able to use this from Python.

Differential Revision: https://phab.mercurial-scm.org/D9297

<item>
    <title>{inbranch%"{if(name, '[{name|escape}] ')}"}{branches%"{if(name, '[{name|escape}] ')}"}{desc|strip|firstline|strip|escape}</title>
    <guid isPermaLink="true">{urlbase}{url|urlescape}rev/{node|short}</guid>
    <link>{urlbase}{url|urlescape}rev/{node|short}</link>
    <description>
    <![CDATA[
        <table>
            <tr>
                <th style="text-align:left;">changeset</th>
                <td>{node|short}</td>
            </tr>
            <tr>
                <th style="text-align:left;">branch</th>
                <td>{inbranch%"{name|escape}"}{branches%"{name|escape}"}</td>
            </tr>
            <tr>
                <th style="text-align:left;">bookmark</th>
                <td>{bookmarks%"{name|escape}"}</td>
            </tr>
            <tr>
                <th style="text-align:left;">tag</th>
                <td>{tags%"{name|escape}"}</td>
            </tr>
            <tr>
                <th style="text-align:left;vertical-align:top;">user</th>
                <td>{author|obfuscate}</td>
            </tr>
            <tr>
                <th style="text-align:left;vertical-align:top;">description</th>
                <td>{desc|strip|escape|websub|addbreaks|nonempty}</td>
            </tr>
            <tr>
                <th style="text-align:left;vertical-align:top;">files</th>
                <td>{files}</td>
            </tr>
        </table>
    ]]>
    </description>
    <author>{author|obfuscate}</author>
    <pubDate>{date|rfc822date}</pubDate>
</item>