Add cmd/datdump/main.go (#3213)

* Feat: add a new datdump tool

* Refactor: address code review comments

* Refactor: remove export all from main program

use datdump instead

* Refactor: allow spaces in exportlists

e.g. `--exportlists="lista, listb"`

* all: cleanup

* apply review suggestion

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Co-authored-by: database64128 <free122448@hotmail.com>

.gitignore

@@ -8,5 +8,5 @@
 dlc.dat
 
 # Exported plaintext lists.
-dlc.dat_plain.yml
+/*.yml
 /*.txt