Add @throws docs to factory methods in \Drupal\update\ModuleVersion

@guilhermevp thanks for the patch!

+++ b/core/modules/update/src/ModuleVersion.php
@@ -43,6 +43,8 @@
+   * @throws \UnexpectedValueException

we need comments for why the exception is thrown. You can get an idea from the exception message and search in core for example messsages that go with @throws

@guilhermevp thanks for updating the patch. Here are a couple suggestions to make it extra clear to developers who get these exceptions what the problem

The only reason I know these reasons is because I helped add this class(and forgot to add the descriptions at the time 😞)

1. +++ b/core/modules/update/src/ModuleVersion.php
   @@ -43,6 +43,9 @@
   +   *   Thrown when version string has unexpected core prefix.
   

   I think we should add some more context.

   how about
   Thrown when a legacy version string has a core prefix other than "8.x-". For example, version strings such as "7.x-1.0" are not supported.

2. +++ b/core/modules/update/src/ModuleVersion.php
   @@ -100,6 +103,9 @@ private function __construct($major_version, $version_extra) {
   +   *   Thrown when branch is not supported.
   

   I think we should change this because a "supported branch" in Drupal has special meaning.

   For instance 8.9.x is a supported and 8.7.x is not supported currently.

   But the exception here is because the parameter $branch is an invalid string that does not end with "."

   So maybe
   Thrown when $branch invalid because it does not end in "."

Thanks @guilhermevp and @phenaproxima!!!!