Add `./wstools merge`

[ronelm2000]

Adds a merge command to wsmtools.

This command merges two decks into 1 deck; overwriting copies of the source_url to copies of the source2_url cards, if any. The only output is Deck JSON stdout (as there is no destination output).

Format:

./wstools merge source_url source2_url [--with optional,flag,strings]

Sample Command:

# This command will get Deck Data from EncoreDecks and replace base rarity cards with my foil cards.
./wstools merge https://www.encoredecks.com/deck/UFo2ADuKC ./my_foil_cards.json