Complement SCM URL with Scaladex

[exoego]

Unfortuately, number of pom.xml without SCM URL are not small.
Therefore Scala Steward can not include URL/diff URL in PR for such artifacts.

Scaladex neatly know SCM URLs even if pom.xml lacks it.
So let's use Scaladex as a second resource.
Original idea: #82 (comment).

This is not perferct solution since Scaladex do not index non-Scala artifacts (e.g. aws-sdk-java), but definitely improve situations !!

Notes

Only artifact id is used as search query, since the below Scaladex issues.
scalacenter/scaladex#577
scalacenter/scaladex#578

Example PRs

Artifact	Before (no URL or homepage)	After (have SCM URL from Scaladex)
sbt-scalatra	exoego/scala-steward-test-project#39	exoego/scala-steward-test-project#62
sbt-scalajs-crossproject	exoego/scala-steward-test-project#37	exoego/scala-steward-test-project#59
scalatest	exoego/scala-steward-test-project#56	exoego/scala-steward-test-project#61

[codecov]

Codecov Report

Merging #837 into master will increase coverage by 0.49%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##           master     #837      +/-   ##
==========================================
+ Coverage    66.3%   66.79%   +0.49%     
==========================================
  Files          87       92       +5     
  Lines        1279     1265      -14     
  Branches       29       36       +7     
==========================================
- Hits          848      845       -3     
+ Misses        431      420      -11

Impacted Files	Coverage Δ
...la/org/scalasteward/core/application/Context.scala	0% <ø> (ø)	⬆️
...ala/org/scalasteward/core/nurture/NurtureAlg.scala	0% <0%> (ø)	⬆️
...calasteward/core/scaladex/HttpScaladexClient.scala	100% <100%> (ø)
...ain/scala/org/scalasteward/core/util/package.scala	100% <100%> (ø)	⬆️
.../org/scalasteward/core/nurture/UrlMappingAlg.scala	100% <100%> (ø)
...scala/org/scalasteward/core/scaladex/package.scala	100% <100%> (ø)
...a/org/scalasteward/core/scaladex/ScaladexAlg.scala	100% <100%> (ø)
...main/scala/org/scalasteward/core/vcs/package.scala	94.44% <50%> (+32.9%)	⬆️
.../core/repocache/json/JsonRepoCacheRepository.scala	0% <0%> (-45.46%)	⬇️
...main/scala/org/scalasteward/core/util/logger.scala	0% <0%> (-36.37%)	⬇️
... and 26 more

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[exoego]

29df383 attempted to fix "Regex DoS" issue found in Codacy quality review, but the issue remained (maybe false-positive).
So reverted to keep implementation simple.

[fthomas]

I like the idea! One thing I'm wondering is if we could use Scaldex' API instead of using regexes on its HTML pages?

[exoego]

I also prefer using API but could not find API client nor document.
Do you know?

[fthomas]

I've not seen an overview, but at least this endpoint exists: https://index.scala-lang.org/api/search?q=refined&target=JVM&scalaVersion=2.12
Maybe there are others which could be useful for our purpose.

[exoego]

Oops, I wrongly deleted the branch.
I will revisit this feature using Scaladex API.

[fthomas]

I think this would be useful even if we can't use the API. But if we add it, #941 will become more important.