Improve feature configuration

[pedromfedricci]

This PR intends to improve the feature selection for some common use cases. Closes: #271.
Users that would want to:

• 1.1 import http client only;
• 1.2 import ws client only;
• 2.1 import http server only;
• 2.2 import ws server only;
• 3.1 import http client and server only;
• 3.2 import ws client and server only;

The behaviour of the current feature flags is preserved, with one exception (clarification bellow), and adds more flags to provide for those above.
The exception: reexporting RpcModule and SubscriptionSink in the path jsonrpsee::types:: was removed as it is also reexported at root level jsonrpsee:: when server + macro are enabled.
This is to remove the path ambiguity, it also reduces the size of the resulting rlib for servers.
I didn't find the reason for having both paths, if there is I will revert it properly.

This table maps the described use cases against current flags and PR flags:
Note: compiled for x86_64-unknown-linux-gnu in debug mode.

use case	current flag	pr flag	rlib size reduction (%)
1.1	client	http-client	~ 17
1.2	client	ws-client	~ 21
2.1	server	http-server	~ 20
2.2	server	ws-server	~ 26
3.1	client + server	http-client + http-server	~ 11
3.2	client + server	ws-client + ws-server	~ 24

Ty.

[maciejhirsz]

Looks good to me!

[pedromfedricci]

hey! I fixed the comments. ty.

[dvdplm]

@pedromfedricci ty so much for this! Do you mind sorting out the merge conflicts? :)

[pedromfedricci]

oh ok! master changed since I pushed this, didn't notice.
This changes things a bit, would you take a look again? @dvdplm @maciejhirsz
ty!

[maciejhirsz]

Cheers, will merge as soon as CI is done.

[dvdplm]

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[dvdplm]

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