Symfony process constructor fix (#312)

* FIX: #311 Update Symfony process to at least 3.4

* FIX Separate out all command components so Solr_Reindex works in dev mode.

Co-authored-by: Kirk Mayo <kirk.mayo@stats.govt.nz>
Co-authored-by: GuySartorelli <36352093+GuySartorelli@users.noreply.github.com>

composer.json

@@ -25,7 +25,7 @@
         "silverstripe/framework": "^4.10",
         "monolog/monolog": "~1.15",
         "ptcinc/solr-php-client": "^1.0",
-        "symfony/process": "^3.2 || ^4",
+        "symfony/process": "^3.4 || ^4",
         "tractorcow/silverstripe-proxy-db": "~0.1",
         "ext-curl": "*"
     },