add gittag conf for vim plugins, alias confs, fix psql as own package

Vim plugins with gittag source:
- vim-airline, vim-airline-themes, vim-ale, vim-devicons, vim-go
- vim-nerdtree, vim-prettier, vim-rust, vim-sensible, vim-shfmt
- vim-syntastic

rust.vim is a directory symlink to vim-rust, so it shares the same
releases.conf automatically.

Alias confs (alias_of):
- postgresql → postgres
- postgresql-client, postgres-client → psql
- mariadb-server, mariadbd → mariadb
- gnupg → gpg, iterm → iterm2, ziglang → zig
- trippy → trip, powershell → pwsh

Fix: psql is its own package (postgres client), not an alias of
postgres (server). Both use the same GitHub repo
(bnnanet/postgresql-releases) but install different binaries.

psql/releases.conf

@@ -1 +1,3 @@
-alias_of = postgres
+source = github
+owner = bnnanet
+repo = postgresql-releases