Allow splitting/merging translations for Crowdin

[romanz]

This way, we can submit them separately to Crowdin, so that each layout could be translated independently.

Following #4489.

[github-actions]

core UI changes	device test	click test	persistence test
T2T1 Model T	test(screens) main(screens)	test(screens) main(screens)	test(screens) main(screens)
T3B1 Safe 3	test(screens) main(screens)	test(screens) main(screens)	test(screens) main(screens)
T3T1 Safe 5	test(screens) main(screens)	test(screens) main(screens)	test(screens) main(screens)
All	main(screens)

[romanz]

Depends on #4495, to be able to reuse translations.get_translation() function.

[romanz]

The CI failures above are due to 4148e87, which will be removed before merging #4495.

[romanz]

3c44637 is added to resort the ??.json files according to key order, to avoid an unrelated diff when running python crowdin.py merge from 32c99f0 (since it also uses tdir.save_lang(lang, blob_json) to update the translations).

[romanz]

Rebasing over #4516 and adding full split/merge functionality here.

[romanz]

Rebasing over latest main to resolve a conflict (after #4495 was merged):

$ git range-diff HEAD^.. origin/romanz/translations-split^..
-:  --------- > 1:  e9aca6861 docs: make sure changelog fragments end with a period
-:  --------- > 2:  7ee1259aa refactor(core): use layout name for translation font keys
-:  --------- > 3:  8bccc7fd0 chore(core): resort translation JSONs by keys
-:  --------- > 4:  1dae795a9 feat(core): support per-layout untranslated text strings
-:  --------- > 5:  206119953 feat(python): support per-layout translated text strings
1:  536fd6404 = 6:  536fd6404 feat(core): allow splitting/merging translations for Crowdin

[romanz]

Tested by manually modifying cs.json and making sure the changes propagate to and back from Crowdin files:

diff --git a/core/translations/cs.json b/core/translations/cs.json
index 970b02b17..44061b8e3 100644
--- a/core/translations/cs.json
+++ b/core/translations/cs.json
@@ -57,7 +57,12 @@
     "address__confirmed": "Adresa příjemce potvrzena",
     "address__public_key": "Veřejný klíč",
     "address__public_key_confirmed": "Veřejný klíč potvrzen",
-    "address__qr_code": "QR kód",
+    "address__qr_code": {
+      "Bolt": "QR kód B",
+      "Caesar": "QR kód C",
+      "Delizia": "QR kód D",
+      "Eckhart": "QR kód E"
+    },
     "address__title_cosigner": "Další podepisující",
     "address__title_receive_address": "Přijímací adresa",
     "address__title_yours": "Vaše",

[obrusvit]

Tested ACK

[romanz]

Thanks!