[RytoEX]

Description

fetchers: Bound URL regex patterns

Make URL patterns match only within start of line and end of line boundaries.

Motivation and Context

This reduces the possibility of accepting malformed URLs and addresses a possible XSS issue.

How Has This Been Tested?

I tested log files from obsproject.com and cdn.discordapp.com successfully.

The URL formats for gist.github.com and hastebin have changed, so they could not be tested here.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have read the contributing document.
• My code has been run through clang-format.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.