Ensure "dev-" prefix and "-dev" suffix is used correctly

[fredden]

In composer/composer#11770 (comment), it was stated that a dev- prefix means something different than a -dev suffix. This came up because a user was treating these as interchangeable when they aren't. This pull request ensures that a prefix is used for "non-numeric branches" whereas a suffix is used for "numeric branches".

While working on this, I noticed a bug in the "remove leading v" code. I've fixed that here (in a separate commit), but I can equally open a separate pull request if you would prefer.

Follows #1027

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b6c84b1) 96.46% compared to head (c7c706e) 97.96%.

❗ Current head c7c706e differs from pull request most recent head 7f201ca. Consider uploading reports for the commit 7f201ca to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1055      +/-   ##
============================================
+ Coverage     96.46%   97.96%   +1.49%     
- Complexity      196      201       +5     
============================================
  Files            32       32              
  Lines           764      834      +70     
============================================
+ Hits            737      817      +80     
+ Misses           27       17      -10     

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