Fix bug in event monitor where subscriptions would not be terminated properly on WebSocket error

[romac]

Closes: #293

Description

This PR fixes a potential bug where subscriptions would not be terminated properly if the WebSocket client encountered an error because

a) we were emptying the subscriptions vector when passing it to select_all, and
b) we were not closing the client explicitly

To test this PR:

Use the following configuration file:

title = "IBC Relayer Config Example"

[global]
timeout = "10s"
strategy = "naive"

[[chains]]
  id = "chain_A"
  rpc_addr = "localhost:26657"
  account_prefix = "cosmos"
  key_name = "testkey"
  store_prefix = "ibc"
  client_ids = ["clA1", "clA2"]
  gas = 200000
  gas_adjustement = 1.3
  gas_price = "0.025stake"
  trusting_period = "336h"

[[connections]]

In one terminal, spawn a Tendermint node running the KV Store app:

docker run -it --rm -v "/tmp/tendermint:/tendermint" tendermint/tendermint init
docker run -it --rm -v "/tmp/tendermint:/tendermint" -p 26657:26657 tendermint/tendermint node --proxy_app=kvstore

In another terminal, from the relayer-cli folder, run the listen command of the relayer:

$ cargo run -- -c path/to/config/file.toml listen

Expected output:

Oct 06 18:01:35.126  INFO relayer_cli::commands::listen: spawning event monitor for chain.id=chain_A
Oct 06 18:01:35.159  INFO relayer_cli::commands::listen: spawning main event handler
Oct 06 18:01:35.160  INFO relayer::event_monitor: running listener for chain.id=chain_A
Oct 06 18:01:35.160  INFO relayer::event_handler: running IBC Event Handler
Oct 06 18:01:35.343  INFO relayer::event_handler: Chain chain_A pushed {"NewBlock":{"height":"322"}}
Oct 06 18:01:35.863  INFO relayer::event_handler: Chain chain_A pushed {"NewBlock":{"height":"323"}}

…

---

For contributor use:

• Unit tests written
• Added test to CI if applicable
• Updated CHANGELOG_PENDING.md
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Updated relevant documentation (docs/) and code comments
• Re-reviewed Files changed in the Github PR explorer

[codecov-io]

Codecov Report

Merging #290 into master will increase coverage by 23.4%.
The diff coverage is 62.0%.

@@            Coverage Diff            @@
##           master    #290      +/-   ##
=========================================
+ Coverage    13.6%   37.1%   +23.4%     
=========================================
  Files          69     120      +51     
  Lines        3752    7743    +3991     
  Branches     1374    2734    +1360     
=========================================
+ Hits          513    2875    +2362     
- Misses       2618    4561    +1943     
+ Partials      621     307     -314     

Impacted Files	Coverage Δ
modules/src/events.rs	0.0% <0.0%> (ø)
modules/src/ics02_client/events.rs	0.0% <ø> (ø)
modules/src/ics02_client/raw.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/context.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/error.rs	16.6% <0.0%> (-16.7%)	⬇️
modules/src/ics04_channel/error.rs	75.0% <ø> (+50.0%)	⬆️
modules/src/ics04_channel/packet.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/client_def.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/error.rs	75.0% <ø> (+75.0%)	⬆️
modules/src/ics18_relayer/error.rs	0.0% <0.0%> (ø)
... and 218 more

---

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[adizere]

FYI, cargo build on master fails following the work in this PR:

   Compiling relayer v0.0.3 (/Users/adi/Hammers/ibc-rs/relayer)
error[E0432]: unresolved imports `tendermint_rpc::query`, `tendermint_rpc::query`
 --> relayer/src/event_monitor.rs:4:5
  |
4 |     query::EventType, query::Query, Subscription, SubscriptionClient, WebSocketClient,
  |     ^^^^^             ^^^^^ could not find `query` in `tendermint_rpc`
  |     |
  |     could not find `query` in `tendermint_rpc`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: could not compile `relayer`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed

LE: had to do a cargo update and cleanup, then build worked!