dbs-virtio-devices: Clear resources when removing virtio-net and vsock devices

[justxuewei]

This PR implements functionaility of clearing resources for virtio-net and virtio-vsock devices.

For virtio-net devices, the removed resource is its event hanlder.

For virtio-vsock devices, the removed resources are its event handler and a socket on the host.

Fixes: #273

[codecov[bot]]

Codecov Report

Merging #277 (7da8349) into main (804bd6e) will decrease coverage by 0.08%. The diff coverage is 13.04%.

@@            Coverage Diff             @@
##             main     #277      +/-   ##
==========================================
- Coverage   90.51%   90.44%   -0.08%     
==========================================
  Files          82       82              
  Lines       24574    24597      +23     
==========================================
+ Hits        22243    22246       +3     
- Misses       2331     2351      +20     

Flag	Coverage Δ
dbs-address-space	95.30% <ø> (ø)
dbs-allocator	94.98% <ø> (ø)
dbs-arch	96.37% <ø> (ø)
dbs-boot	94.90% <ø> (ø)
dbs-device	92.95% <ø> (ø)
dbs-interrupt	90.42% <ø> (ø)
dbs-legacy-devices	92.77% <ø> (ø)
dbs-miniball	?
dbs-upcall	94.31% <ø> (ø)
dbs-utils	91.25% <ø> (ø)
dbs-virtio-devices	87.34% <13.04%> (-0.13%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
crates/dbs-virtio-devices/src/net.rs	85.71% <0.00%> (-0.86%)	:arrow_down:
crates/dbs-virtio-devices/src/vsock/device.rs	79.49% <0.00%> (-3.48%)	:arrow_down:
...bs-virtio-devices/src/vsock/backend/unix_stream.rs	95.45% <100.00%> (+0.10%)	:arrow_up:

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[studychao]

please help fix the clippy warnings.