Add version extension and semantic versioning support

[chris-doehring]

What is the reason for this PR?

For a long time I wanted some sort of version generator in Faker. #335 reminded me of that idea, so I tried to implement it, but only the semantic versioning syntax for now. (Others may follow later)

• A new feature

Author's checklist

• Follow the Contribution Guide
• New features and changes are documented (Add docs for semver function fakerphp.github.io#47)

Summary of changes

• Added a new version extension and registered it in the Generator
• Added semver method to version extension and registered it in the Generator
• Added a test case

Some examples from the random generation:

9.21.81+1343915
0.62.59+20031002130830
5.94.22+eb3fa72
2.74.43+20021105093641
2.55.51-beta
4.83.31+cc71761
3.81.0
9.13.97+6ad6819
2.63.18
0.49.31-rc.97+20170720134141

Review checklist

• All checks have passed
• Changes are approved by maintainer

[pimjansen]

Good work @chris-doehring. Will review asap

[pimjansen]

Lgtm!

[pimjansen]

Thanks @chris-doehring