Remove sdk before readd due prb with subtree merges.
Add 'sdk/php/src/' from commit 'd90a3574c3a3eb7a4cbba490e6c614d44dfb06f6'

git-subtree-dir: sdk/php/src
git-subtree-mainline: 93a4ea9763706a82c3fe7173b3f4fde7746cebb0
git-subtree-split: d90a3574c3a3eb7a4cbba490e6c614d44dfb06f6