feat(appservice): Add default request config

[emgrav]

Adds an optional default RequestConfig to the appservice struct, which when present is used for any virtual clients created.

Closes #925

[codecov]

Codecov Report

Base: 78.46% // Head: 78.41% // Decreases project coverage by -0.04% ⚠️

Coverage data is based on head (39444db) compared to base (2818551).
Patch coverage: 30.76% of modified lines in pull request are covered.

❗ Current head 39444db differs from pull request most recent head 7417d86. Consider uploading reports for the commit 7417d86 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #998      +/-   ##
==========================================
- Coverage   78.46%   78.41%   -0.05%     
==========================================
  Files         110      110              
  Lines       15121    15133      +12     
==========================================
+ Hits        11864    11867       +3     
- Misses       3257     3266       +9     

Impacted Files	Coverage Δ
crates/matrix-sdk-appservice/src/lib.rs	90.66% <30.76%> (-2.47%)	⬇️

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[jplatte]

Thanks for the PR!

Would be good if the change to a builder pattern was a separate commit or even PR. Also there should be AppService::builder like there is Client::builder, so one doesn't have to import the builder type for common usage.

[emgrav]

Opened a new PR for the builder pattern with the requested changes in #1051.

[jplatte]

With #1051 merged, this is now waiting on a rebase.

[jplatte]

Looks good now, just one nitpick.

[jplatte]

This isn't actually a breaking change now that the conversion to builder pattern has already happened, right?