Support vault 1.19+ "Indirect value references" for seal transit token file copying

[ron1]

Vault 1.19+ introduces Indirect value references. Enhance seal transit token management by introducing support for remote copying a seal transit token file. This token file would then be referenced by setting variable value_transit_tokento indirect value reference file:///<path-to-transit-token-file.

Consider modifying existing variable vault_transit_token and introducing two new vault_transit_token-specific variables as follows:

• vault_transit_token
  -- Token used to authenticate to the external vault instance.
  -- Either this or vault_transit_token_src_file must be set if vault_transit is enabled.
  -- Default value: ''
• vault_transit_token_src_file
  -- Path to Vault Transit Token file on Ansible control node.
  -- Either this or vault_transit_token must be set if vault_transit is enabled.
  -- Default value: ''
• vault_transit_token_dst_file
  -- Path to Vault Transit Token file on Vault server.
  -- Must be set if vault_transit_src_file is set.
  -- Default: value: "{{ vault_home }}/{{ vault_transit_token_src_file | basename }}"