test: adapt tests to the pre-approval flow

[SebastianElvis]

Resolves #121
Resolves #119

This PR adapts the tests under x/btcstaking to the pre-approval flow. This includes

• generalising the h.CreateDelegation function to support both pre-approval and non-pre-approval flow
• new test util function for submitting inclusion proof
• adapt most of the tests to use pre-pre-approval

In addition, this PR proposes to rename status VERIFIED to APPROVED for clarity: verified is a bit generic while approved is more consistent with existing terms (pre-"approval"). Also this PR fixes the flaky FuzzBTCDelegation test (checked the fix via fuzzing locally).

[KonradStaniec]

In addition, this PR proposes to rename status VERIFIED to APPROVED for clarity: verified is a bit generic while approved is more consistent with existing terms

ah we wanted to specifically avoid the word approval (https://github.com/babylonlabs-io/pm/pull/48#issuecomment-2382252055) as it has some negative connotations. In reality covenant members do not approve anything. Their job is to:

1. verify transactions
2. send signatures
   hence VERIFIED sounded like a good candidate. Do you maybe have other ideas for naming ?

[SebastianElvis]

In reality covenant members do not approve anything.

Actually I thought the opposite: covenant committee indeed approves BTC delegations, and they can selectively approve and disapprove. Hence the feature we are adding is called pre-approval.

Although I agree that the word does not sound right politically. Let me change it back (UPDATE: fixed)

[KonradStaniec]

LGTM!