title: own typo3 Extension doesn't get shown in Extension Manager (Composer Mode)
body: <p>Im trying to set up my own Extension, for having in the all kind of changes to my Site. I set up typo3 9.5.5 via. Composer. The next step was building up my own extension. I followed the official docs and also added a composer.json, but it wont show up in the Extension Manager.</p>
  <h3>ext_emconf</h3>
  <pre><code>&lt;?php
  $EM_CONF[$_EXTKEY]=[
  'title'=&gt;'MS Site Extension',
  'description'=&gt;'TYPO3 Site Extionsion',
  'category'=&gt;'plugin',
  'author'=&gt;'-',
  'author_company'=&gt;'-',
  'author_email'=&gt;'-',
  'state'=&gt;'alpha',
  'clearCacheOnLoad'=&gt;true,
  'version'=&gt;'0.0.1',
  'constraints'=&gt;[
    'depends'=&gt;[
      'typo3'=&gt;'9.5.5-9.9.99',
    ],
  ],
  'autoload'=&gt;[
    'psr-4'=&gt;[
      'Ms\\MsSite\\'=&gt;'Classes'
    ],
  ],
  ]; 
  </code></pre>
  <h3>composer.json of the extension</h3>
  <pre><code>{
  &quot;name&quot;: &quot;ms/ms_site&quot;,
  &quot;type&quot;: &quot;typo3-cms-extension&quot;,
  &quot;description&quot;: &quot;MS SITE&quot;,
  &quot;license&quot;: [
  &quot;GPL-2.0+&quot;
  ],
  &quot;keywords&quot;: [
    &quot;typo3&quot;,
    &quot;cms&quot;,
    &quot;ms&quot;,
    &quot;ms_site&quot;
  ],
  &quot;version&quot;: &quot;0.0.1-dev&quot;,
  &quot;require&quot;: {
    &quot;typo3/cms&quot;: &quot;^9.5&quot;
  },
  &quot;autoload-dev&quot;: {
    &quot;psr-4&quot;: {
      &quot;Ms\\MsSite\\&quot;: &quot;Classes/&quot;
    },
    &quot;replace&quot;: {
      &quot;hellotypo3&quot;: &quot;self.version&quot;,
      &quot;typo3-ter/ms_site&quot;: &quot;self.version&quot;
    },
    &quot;extra&quot;: {
      &quot;typo3/cms&quot;: {
        &quot;extension-key&quot;: &quot;ms_site&quot;
      }
    }
  }
  }
  </code></pre>
  <p>I'm a bit confused what I have to do now, the only place where my extension currently is, is at: typo3conf/ext, I configured it in the ext_emconf and the composer.json of the extension.</p>
  <p>How do I solve this problem?</p>
  <p>Edit: Hmm my console tells me that ms_site is added to PackageStates but I still can't see my Extension in my Backend ...</p>
  <p><a href="https://i.stack.imgur.com/v3NLf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/v3NLf.png" alt="enter image description here" /></a></p>