Adapt the Secrets plugin API to use kubernetes secrets #19837
Description
Is your task related to a problem? Please describe.
The Secrets plugin API is going to be merged soon to theia. It uses keytar to store data in the local file system. This approach will not work for Che because workspaces are containers with new OS each time they restart, so the data will go away on restart.
Describe the solution you'd like
Reimplement the CredentialsService to use kubernetes secrets.