fix(vault): parse pre-v0.23 vault secrets

[ecrupper]

If a vault secret has not been updated since before v0.23, it will not have allow_events or allow_substitution. We can infer these values by converting event slice into the allow events mask and by setting substitution setting to the same setting as the command setting.

I didn't include any update process on the Vela side. Fortunately the UI submits the entire secret form on update, so users will slowly update their vault secrets on their own accord.

We could also consider creating a migration script of sorts to prevent this code, but we're also supporting v1 and v2 of Vault in code as well. Not saying that's an excuse, but perhaps revisiting our backwards compatibility in general could be a good future issue 🤷

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 62.64%. Comparing base (0c3e620) to head (1aed673).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1086      +/-   ##
==========================================
+ Coverage   62.60%   62.64%   +0.03%     
==========================================
  Files         345      345              
  Lines       10277    10304      +27     
==========================================
+ Hits         6434     6455      +21     
- Misses       3367     3373       +6     
  Partials      476      476              

Files	Coverage Δ
secret/vault/vault.go	94.05% <77.77%> (-2.79%)	⬇️

[jbrockopp]

LGTM