feat: pass records limit on routing.FindProviders

[hacdias]

While working on ipfs/kubo#9877, I noticed that the ContentRouter interface required in order to implement the Routing V1 server does not provide enough information to make an education decision about how many providers to return.

This did not use to be an issue because the API was non-streamed so we could hardcode a value on the implementation (or timeout). Now that the server also supports streaming requests, it would be great to be able to differentiate both.

After talking to @lidel, we talked about adding a count int parameter in the FindProviders. By default, count will be 20 for non-streamable requests and 0 (unbounded) for streaming requests. However, I find that that introduces unnecessary complexity here. So I just added a stream bool parameter to FindProviders instead, and we let the implementer of ContentRouter decide what to do with it. See #299 (comment).

Note that existing tests that I updated test this too.

[codecov]

Codecov Report

Merging #299 (a3c134b) into main (1daddd8) will decrease coverage by 0.57%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main     #299      +/-   ##
==========================================
- Coverage   48.15%   47.59%   -0.57%     
==========================================
  Files         279      276       -3     
  Lines       33524    33467      -57     
==========================================
- Hits        16145    15928     -217     
- Misses      15690    15849     +159     
- Partials     1689     1690       +1     

Impacted Files	Coverage Δ
routing/http/server/server.go	65.38% <50.00%> (-1.63%)	⬇️

... and 19 files with indirect coverage changes

[lidel]

Configurable limit of returned responses lgtm, makes it more useful as a library, thanks!