Add support for proxying TCP apps

[r0mant]

This PR adds support for proxying TCP applications in App Access. Closes #10216. Also closes #10952.

Users can define a TCP application same way as they define HTTP apps, for example in the static config or using dynamic registration:

app_service:
  enabled: "yes"
  apps:
  - name: "ponger"
    description: "Ping pong"
    uri: tcp://localhost:9876
  - name: "postgres"
    description: "PostgreSQL"
    uri: tcp://localhost:5432

tsh apps ls now specifies the application protocol:

$ tsh apps ls
Application  Description   Type Public Address                   Labels
------------ ------------- ---- -------------------------------- ----------------------------------
dumper       Header dumper HTTP dumper.root.gravitational.io     app=dumper,teleport.dev/origin
elastic      Elasticsearch HTTP elastic.root.gravitational.io    app=elastic,teleport.dev/origin
opensearch   OpenSearch    HTTP opensearch.root.gravitational.io app=opensearch,teleport.dev/origin
ponger       Ping pong     TCP  ponger.root.gravitational.io     app=ponger,teleport.dev/origin
postgres     PostgreSQL    TCP  postgres.root.gravitational.io   teleport.dev/origin

After fetching credentials for a TCP application, a user starts a local proxy:

$ tsh app login postgres
Logged into TCP app postgres. Start the local TCP proxy for it:

  tsh proxy app postgres

Then connect to the application through this proxy.

$ tsh proxy app postgres
Proxying connections to postgres on 127.0.0.1:54720

Then they can connect to the local proxy with the app's client as if they were connecting to the app directly:

$ psql postgres://r0mant@localhost:54720/test
psql (14.2, server 13.5 (Debian 13.5-1.pgdg110+1))
Type "help" for help.

test=#

Docs and the webapps PR to update UI for the new audit event will come separately.

[smallinsky]

First pass, I have left some suggestions.

[r0mant]

@rosstimothy @smallinsky @alistanis Sorry about the delay folks, just got a chance to address your comments. PTAL.

[github-actions]

@r0mant See the table below for backport results.

Branch	Result
branch/v10	Failed

[jingsunnews]

This method can be used to connect Redshift with Redshift jdbc driver (not postgres driver).