Provide a way to limit max number of requests and max connection age for client

[ikhoon]

Motivation:

A long connection can cause load imbalance between servers if clients do not use client-side balance.
Because L4 load balancers keep a client connection to a server.

The traffic could be rebalanced by closing connections periodically or after N requests.
A max connection age for server-side was added by #2747.
However max connection age for client and max number of requests for server and client have not implemented yet.

Related: #203 #2741 #2747

Modifications:

• Add maxNumRequestsPerConnection to ServerBuilder, ClientFactoryBuilder and Flags
  • Send GOAWAY or Connection: close by server-side
  • Remove from channel pool and close a connection or send GOAWAY by client-side
• Add maxConnnectionAge{Millis} to ClientFactoryBuilder and Flags
• Keep track of requests count by KeepAliveHandler to determine a connection is needed to close
• Remove some fields, derived from ClientFatory, in HttpChannelPool and
  pass ClientFactory to HttpSessionHandler for reducing object size and simplicity.
• Add MaxConnectionAgeExceededTask to close an expired connection.

Result:

• You can now set a maximum allowed number of requests for a connection.

  // For server
  Server.builder()
        // A connection will be closed after serving 10000 requests.
        .maxNumRequestsPerConnection(10000);
  
  // For client
  ClientFactory.builder()
               // A connection will be closed after fully receiving the response of 2000th requests.
               .maxNumRequestsPerConnection(2000);

• You can now set a maximum allowed connection age for a connection on client-side.

  // A connection will be closed in 10 seconds after the connection is established.
  ClientFactory.builder()
               .maxConnnectionAgeMillis(10000);

• Fixes Automatic disconnection after handling N requests #203

Co-authored-by: julie-kim julie.kim@linecorp.com

[codecov]

Codecov Report

Merging #3267 (cc55c0c) into master (7fdbddb) will decrease coverage by 0.07%.
The diff coverage is 82.32%.

@@             Coverage Diff              @@
##             master    #3267      +/-   ##
============================================
- Coverage     74.10%   74.02%   -0.08%     
- Complexity    13015    13085      +70     
============================================
  Files          1136     1143       +7     
  Lines         49276    49661     +385     
  Branches       6256     6303      +47     
============================================
+ Hits          36515    36761     +246     
- Misses         9546     9657     +111     
- Partials       3215     3243      +28     

Impacted Files	Coverage Δ	Complexity Δ
...ecorp/armeria/client/ClientHttp2ObjectEncoder.java	37.83% <0.00%> (ø)	8.00 <0.00> (+2.00)
...rp/armeria/client/Http1ClientKeepAliveHandler.java	100.00% <ø> (ø)	6.00 <0.00> (ø)
...rp/armeria/client/Http2ClientKeepAliveHandler.java	100.00% <ø> (ø)	2.00 <0.00> (ø)
...orp/armeria/internal/common/HttpObjectEncoder.java	63.63% <ø> (ø)	10.00 <0.00> (ø)
...rp/armeria/server/Http2ServerKeepAliveHandler.java	75.00% <ø> (ø)	3.00 <0.00> (ø)
...ecorp/armeria/server/ServerHttp2ObjectEncoder.java	79.41% <33.33%> (-5.89%)	15.00 <1.00> (-1.00)
.../linecorp/armeria/client/Http2ResponseDecoder.java	68.61% <50.00%> (-2.16%)	44.00 <7.00> (+4.00)	⬇️
...armeria/internal/common/Http1KeepAliveHandler.java	50.00% <50.00%> (ø)	1.00 <1.00> (?)
...ecorp/armeria/server/ServerHttp1ObjectEncoder.java	83.33% <50.00%> (-3.21%)	21.00 <0.00> (+1.00)	⬇️
.../linecorp/armeria/client/Http1ResponseDecoder.java	66.66% <66.66%> (-0.22%)	43.00 <6.00> (-1.00)
... and 57 more

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