mxisd supports several identity stores. Add support to configure two of them:
* synapseSql (storing identities directly in Synapse's database)
* LDAP
This removed the need to copy `mxisd.yaml.j2` to the inventory in case one wants
to use LDAP as identity store. Note that the previous solution (copying
`mxisd.yaml.j2` was poor because of two reasons:
* The copy remains outdated in case the original is updated in future versions
of this repo.
* The role's configuration should be in one place (configured only through role
variables) instead of in multiple.
Configuring more identity stores through role variables can be supported in the
future.
haslersn
Slavi Pantaleev