Correctly generate http response codes

[82marbag]

http response codes will be:

• @httpResponseCode if set
• @http's code, if @httpResponseCode is not set
• the default one, if neither of the above are set

@httpResponseCode honors @required and generates code that
doesn't use Option when applied.

Closes: #1229

Motivation and Context

Description

• set http response status to using Option only when not @required
• default to @http's code when the status is not set
• default to the builder's default if none is set
• add tests

Testing

./gradlew :codegen-server-test:test && ./gradlew :codegen-test:test

Checklist

• I have updated CHANGELOG.next.toml if I made changes to the smithy-rs codegen or runtime crates
• I have updated CHANGELOG.next.toml if I made changes to the AWS SDK, generated SDK code, or SDK runtime crates

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

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• AWS SDK (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)

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Rust Wrk benchmark report:

Duration: 90 sec, Connections: 32, Threads: 2

Measurement	Deviation	Current	Old
Requests/sec	-0.75%	39184.97	39482.42
Total requests	-0.77%	3527659	3554925
Total errors	NaN%	0	0
Total successes	-0.77%	3527659	3554925
Average latency ms	1.19%	0.85	0.84
Minimum latency ms	0.00%	0.02	0.02
Maximum latency ms	-6.96%	16.71	17.96
Stdev latency ms	11.32%	0.59	0.53
Transfer Mb	-0.77%	366.7	369.54
Connect errors	NaN%	0	0
Read errors	NaN%	0	0
Write errors	NaN%	0	0
Status errors (not 2xx/3xx)	NaN%	0	0
Timeout errors	NaN%	0	0

[github-actions]

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• AWS SDK (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)

A new doc preview is ready to view.

Rust Wrk benchmark report:

Duration: 90 sec, Connections: 32, Threads: 2

Measurement	Deviation	Current	Old
Requests/sec	10.28%	80850.82	73311.07
Total requests	10.30%	7280188	6600478
Total errors	NaN%	0	0
Total successes	10.30%	7280188	6600478
Average latency ms	114.81%	1.16	0.54
Minimum latency ms	0.00%	0.02	0.02
Maximum latency ms	38.95%	23.65	17.02
Stdev latency ms	142.68%	1.99	0.82
Transfer Mb	10.30%	756.78	686.12
Connect errors	NaN%	0	0
Read errors	NaN%	0	0
Write errors	NaN%	0	0
Status errors (not 2xx/3xx)	NaN%	0	0
Timeout errors	NaN%	0	0

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)

A new doc preview is ready to view.

Rust Wrk benchmark report:

Duration: 90 sec, Connections: 32, Threads: 2

Measurement	Deviation	Current	Old
Requests/sec	-2.52%	69881.78	71685.08
Total requests	-2.59%	6289900	6457457
Total errors	NaN%	0	0
Total successes	-2.59%	6289900	6457457
Average latency ms	1.75%	0.58	0.57
Minimum latency ms	0.00%	0.02	0.02
Maximum latency ms	-4.63%	16.47	17.27
Stdev latency ms	-5.13%	0.74	0.78
Transfer Mb	-2.60%	653.84	671.26
Connect errors	NaN%	0	0
Read errors	NaN%	0	0
Write errors	NaN%	0	0
Status errors (not 2xx/3xx)	NaN%	0	0
Timeout errors	NaN%	0	0

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)

A new doc preview is ready to view.

Rust Wrk benchmark report:

Duration: 90 sec, Connections: 32, Threads: 2

Measurement	Deviation	Current	Old
Requests/sec	-4.60%	70583.15	73986.16
Total requests	-4.64%	6355069	6664497
Total errors	NaN%	0	0
Total successes	-4.64%	6355069	6664497
Average latency ms	-21.25%	0.63	0.8
Minimum latency ms	0.00%	0.02	0.02
Maximum latency ms	-14.94%	17.36	20.41
Stdev latency ms	-32.03%	0.87	1.28
Transfer Mb	-4.64%	660.61	692.78
Connect errors	NaN%	0	0
Read errors	NaN%	0	0
Write errors	NaN%	0	0
Status errors (not 2xx/3xx)	NaN%	0	0
Timeout errors	NaN%	0	0