Theia 1.16.0

See theia's changelog, we update from 1.13.0 to 1.16.0.

Changes specific to slapos port:

• We set warnOnPotentiallyInsecureHostPattern because the new warning is very intrusive ... but it might actually be very insecure. For now we don't have solution. We are tracking this in https://erp5js.nexedi.net/#/bug_module/20210819-20614EE
• New libsecret component that is now required by theia
• Switch to using vscode git instead of theia git, to use timeline ( see https://github.com/eclipse-theia/theia/pull/7997 )
• globally version up slapos.core to https://pypi.org/project/slapos.core/1.6.18/