Create psql templates to reduce boilerplace

[stavros-k]

Moved some pgsql boilerplate to templates

---

A before and after shows that no changes are in the rendered manifests.
(Expect some autogenerated values which are unrelated with the postgres template)

❯ diff before.yaml after.yaml 
18,19c18,19
<   DATABASE_URL: postgres://briefkasten:9whT917ZrY7u07RBtkdM25K2ZWzgK0Mo@release-name-briefkasten-postgres:5432/briefkasten?sslmode=disable
<   NEXTAUTH_SECRET: 1tSDP7nXPIrUa8rRADCbGy2ncNug2mSxPjvcsbXKYN8h34m2aUclEpSNyN3jU9fp
---
>   DATABASE_URL: postgres://briefkasten:WHBmBy8O6TCKddnSCy1sgfkt0YOfGbM8@release-name-briefkasten-postgres:5432/briefkasten?sslmode=disable
>   NEXTAUTH_SECRET: 6OlGAqXY2IlGDyUfelFlVwDkKPIcqw8Ys7yJRlASPDoYXhdZfAqoIoq1ippKs9iy
41,42c41,42
<   POSTGRES_PASSWORD: 9whT917ZrY7u07RBtkdM25K2ZWzgK0Mo
<   POSTGRES_URL: postgres://briefkasten:9whT917ZrY7u07RBtkdM25K2ZWzgK0Mo@release-name-briefkasten-postgres:5432/briefkasten?sslmode=disable
---
>   POSTGRES_PASSWORD: WHBmBy8O6TCKddnSCy1sgfkt0YOfGbM8
>   POSTGRES_URL: postgres://briefkasten:WHBmBy8O6TCKddnSCy1sgfkt0YOfGbM8@release-name-briefkasten-postgres:5432/briefkasten?sslmode=disable
171c171
<         rollme: "7tNbe"
---
>         rollme: "N43vO"
407c407
<         rollme: "uBT1v"
---
>         rollme: "CiJ3t"
608c608
<         rollme: "mmzT4"
---