Add a .gitattributes file to all repositories

Add export-ignore to reduce size of archive

• /.gitattributes export-ignore
• /.github/ export-ignore
• /.gitignore export-ignore
• /docs/ export-ignore
• /phpcs.xml export-ignore
• /phpunit.xml.dist export-ignore
• /psalm.xml export-ignore
• /psalm-baseline.xml export-ignore
• /test/ export-ignore

Add more files as necessary