Appease Clippy's unnecessary_lazy_evaluations in Rust 1.60

[david-perez]

In Rust 1.60 we get Clippy lint warnings that make the build fail.

warning: unnecessary closure used to substitute value for `Option::None`
   --> inlineable/src/json_errors.rs:98:25
    |
98  |       if let Some(code) = error_type_from_header(headers)
    |  _________________________^
99  | |         .map_err(|_| DeserializeError::custom("X-Amzn-Errortype header was not valid UTF-8"))?
100 | |         .or_else(|| code.as_deref())
    | |____________________________________^
    |
    = note: `#[warn(clippy::unnecessary_lazy_evaluations)]` on by default
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations
help: use `or` instead
    |
98  ~     if let Some(code) = error_type_from_header(headers)
99  +         .map_err(|_| DeserializeError::custom("X-Amzn-Errortype header was not valid UTF-8"))?.or(code.as_deref())

Since len is cheap and deref is supposed to be cheap, these resolve
to reading a pointer in assembly and they don't need to be lazily
evaluated.

https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations
rust-lang/rust-clippy#8109
https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/eager_or_lazy.rs

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[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

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	6.37%	81360.75	76485.52
Total requests	6.31%	7323907	6889432
Total errors	NaN%	0	0
Total successes	6.31%	7323907	6889432
Average latency ms	44.87%	1.13	0.78
Minimum latency ms	0.00%	0.02	0.02
Maximum latency ms	12.91%	21.69	19.21
Stdev latency ms	54.47%	1.9	1.23
Transfer Mb	6.31%	761.32	716.16
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

[david-perez]

But CI of course doesn't like this until we upgrade from 1.58.

[Velfi]

We can up the MSRV when they release 1.62 in a few weeks and then merge this.