build: Add GitLab CI/CD config

.gitignore

 target/
 classes/
+.idea
\ No newline at end of file

.gitlab-ci.yml

+include:
+  - project: 'VIPS/vips-common-config'
+    file: '/gitlab-ci-vips-models.yml'
+    ref: main
\ No newline at end of file

ci_settings.xml

+<settings xmlns="http://maven.apache.org/SETTINGS/1.1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.1.0 http://maven.apache.org/xsd/settings-1.1.0.xsd">
+    <servers>
+        <server>
+            <id>gitlab-maven</id>
+            <configuration>
+                <httpHeaders>
+                    <property>
+                        <name>Job-Token</name>
+                        <value>${CI_JOB_TOKEN}</value>
+                    </property>
+                </httpHeaders>
+            </configuration>
+        </server>
+    </servers>
+</settings>
\ No newline at end of file