Add basic support for UDTs, Enums and Domains

[rocket-3]

Added template code for UDTs, Enums and Domains Meta/DB objects support
DBEnum/DBUserDefinedType/DBDomain are instances of MetaSql, that's why no modification in Backup adapters needed
Added template code for Postgres DBMS implementation of fetching these obejcts data

[rocket-3]

Now we have some implementation of fetching and restore of custom types.
Let's run fetch scenario test case DbGitIntegrationTestBasic#dbToFilesDumpWorks (which now uses dvdrental database and configures .dbignore to take custom types)

[rocket-3]

@rultor merge, tests=*IntegrationTest*#*dbToFilesDumpWorks*

[rultor]

@rultor merge, tests=*IntegrationTest*#*dbToFilesDumpWorks*

@rocket-3 OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge, tests=*IntegrationTest*#*dbToFilesDumpWorks*

@rocket-3, tests OK. You can see the full log here (spent 2min)

|   /home/r/repo/target/itoutput/02 # writing file .dbgit/.dbignore with content:
|   > *
|   > !public/*.ts
|   > !public/*.sch
|   > !public/*.seq
|   > !public/*.tbl
|   > !public/*.pkg
|   > !public/*.trg
|   > !public/*.prc
|   > !public/*.fnc
|   > !public/*.vw
|   > !public/*.blob
|   > !public/*.udt
|   > !public/*.enum
|   > !public/*.domain
|   > !public/*.csv
|   /home/r/repo/target/itoutput/02 # /home/r/repo/target/dbgit/bin/dbgit add "*"
|   > Done!
|   [TEST OK] "git folder exists"
|   [TEST OK] "rental table data exists"
|   [TEST OK] "city table data (small) is not empty"
|   [TEST OK] "rental table data (10K+ rows) exists and is empty"
|   [TEST OK] "mpaa_rating.enum exists"
|   [TEST OK] "year.domain exists"
|   [TEST OK] "film_summary.udt exists"
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 32.06 s - in 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
container 7a2cffa31de40f3083e607a71bbc538a6041b4831e8efc5a76552ae9c85173cf is dead
Fri Jun 11 03:12:25 CEST 2021