ipc mining: pass missing context to BlockTemplate methods (incompatible schema change)

Adding a context parameter ensures that these methods are run in
their own thread and don't block other calls. They were missing
for:

- createNewBlock()
- checkBlock()

The missing parameters were first pointed out by plebhash in
https://github.com/bitcoin/bitcoin/issues/33575#issuecomment-3383290115 and
adding them should prevent possible performance problems and lockups,
especially with #34184 which can make the createNewBlock method block for a
long time before returning. It would be straightforward to make this change in
a backward compatible way
(https://github.com/bitcoin/bitcoin/pull/34184#discussion_r2770232149) but nice
to not need to go through the trouble.

Warning: This is an intermediate, review-only commit. Binaries built from it
should not be distributed or used to connect to other clients or servers. It
makes incompatible changes to the `mining.capnp` schema without updating the
`Init.makeMining` version, causing binaries to advertise support for a schema
they do not actually implement. Mixed versions may therefore exchange garbage
requests/responses instead of producing clear errors. The final commit in this
series bumps the mining interface number to ensure mismatches are detected.

git-bisect-skip: yes

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>

test/functional/test_framework/ipc_util.py

@@ -108,7 +108,7 @@ async def make_capnp_init_ctx(self):
 
 async def mining_create_block_template(mining, stack, ctx, opts):
     """Call mining.createNewBlock() and return template, then call template.destroy() when stack exits."""
-    response = await mining.createNewBlock(opts)
+    response = await mining.createNewBlock(ctx, opts)
     if not response._has("result"):
         return None
     return await stack.enter_async_context(destroying(response.result, ctx))