Bump Rust compiler to 1.73.0 and update uniffi to 0.25.1

[thunderbiscuit]

This PR fixes a number of longstanding issues with uniffi, the Rust compiler, and the Android NDK. In short, it updates all 3 to new versions:

1. Bumps NDK to 25.2.9519653
2. Bumps Rust compiler to 1.73.0
3. Bumps uniffi to 0.25.1
4. Removes the need to use nightly for the Swift builds.

Fixes #413
Fixes #243
Fixes #242
Will help get #282 in.

We have two main reasons for bumping the uniffi version:

1. The 0.24 version of uniffi bring in async support, which we want to use for the async Esplora client.
2. The 0.25.X version of uniffi will bring inline API docs, and this is an important feature for the 1.0 release. We have decided to deprecate and not keep supporting the custom-built API docs maintained in the api-docs directory. Progress on the merging of this can be tracked mostly on Support for generation of documentation comments for bindings mozilla/uniffi-rs#1498

And one reason to bump the NDK:

1. Android emulator CI tests must be run on macos images, and we must use a later version of the NDK with them.

[thunderbiscuit]

I have tested the library locally on a version of the Devkit Wallet. This is a fairly important update across 3 different dimensions; happy to report that everything seems to work well.

[reez]

I was able to build the bdk-swift library locally (on my M1 😢 on both a M1 and M3 😅).

I then tested the library locally on a simplified version of BDKSwiftExampleWallet, able to create the wallet and sync the balance properly, so seems to be working well.

[notmandatory]

ACK f2cd561

[reez]

ACK f2cd561

[tnull]

So I confirmed that we can also easily upgrade LDK Node to Uniffi 0.25.1 (see lightningdevkit/ldk-node#190) and bindings interop should at least not be blocked on version mismatch. Thanks for checking in!