Update a contact on re-import rather than skipping it

#228 skipped a vCard whose UID the book already held. The reporter asked for
the opposite on #174 and he is right: the reason to import a file a second
time is usually that the first one was not right, so skipping means a
corrected export corrects nothing.

A merge, not a replacement. Properties the file carries overwrite what is
here; properties it does not mention are left alone, so a phone number added
in ihasmail after the first import survives a re-import of the original file.
The cost is that a field genuinely deleted at the source stays here, which is
the better way to be wrong -- the other way round loses work nobody asked to
lose. Worth confirming with him rather than assuming.

`addressBookIds` is left off the patch. The card is already in this book, so
saying it again says nothing, and saying it on a card that is also in another
book would move it.

Creates and updates now share one batch budget. Stalwart counts every object
in a /set together, so batching the halves separately would send 300 new and
300 changed as two calls of 300 and be refused for a limit of 500 that neither
half exceeds.

LDIF is untouched and still reports look-alikes without acting on them, since
what it should match on is the question still open on #223. Both imports keep
one answer shape so a caller need not know which it called; LDIF's `updated`
is always 0, which is the honest number rather than a missing field.

The message a vCard attached to a message shows changes with it: the newer
copy now wins instead of being dropped, so it says the contact was brought up
to date rather than that nothing was added.

Refs #223.

web/src/store/__tests__/ldif-import.test.ts

@@ -63,7 +63,7 @@ describe("importing an LDIF address book", () => {
   it("creates every entry in one call, not one call each", async () => {
     const sets = server();
     const n = await useContacts.getState().importLdif(TWO, "book1");
-    expect(n).toEqual({ created: 2, skipped: 0, alike: 0 });
+    expect(n).toEqual({ created: 2, updated: 0, alike: 0 });
     expect(sets).toHaveLength(1);
     expect(Object.keys(sets[0]!.create!)).toEqual(["c0", "c1"]);
   });
@@ -105,7 +105,7 @@ describe("importing an LDIF address book", () => {
   it("skips entries too empty to be a person, and imports the rest", async () => {
     const sets = server();
     const n = await useContacts.getState().importLdif(`${TWO}\ndn: cn=Nobody\nobjectClass: top\n`, "book1");
-    expect(n).toEqual({ created: 2, skipped: 0, alike: 0 });
+    expect(n).toEqual({ created: 2, updated: 0, alike: 0 });
     expect(Object.keys(sets[0]!.create!)).toHaveLength(2);
   });
 
@@ -116,6 +116,6 @@ describe("importing an LDIF address book", () => {
 
   it("counts what got in when only some of it did", async () => {
     server({ notCreated: { c1: { type: "invalidProperties" } } });
-    await expect(useContacts.getState().importLdif(TWO, "book1")).resolves.toEqual({ created: 1, skipped: 0, alike: 0 });
+    await expect(useContacts.getState().importLdif(TWO, "book1")).resolves.toEqual({ created: 1, updated: 0, alike: 0 });
   });
 });