ASP.NET Core Browser Injection: Implement RUM script injection logic

[tippmar-nr]

Describe the story, please be clear on scope of the story.

The POC branch currently only looks for the </head> tag and injects the RUM script just prior to it.

Implement logic for ASP.NET Core 6+ that is similar to (or perhaps re-uses) the existing logic used for injecting the RUM script for ASP.NET in Framework applications, where several potential locations for injecting the script are considered.

Also add unit tests in RumLoaderInsertionLocationTests to exercise the cross-agent test scenarios for RUM script placement.

Acceptance Criteria

The RUM script is injected properly in ASP.NET Core 6+ web applications in various situations, with logging to indicate success or failure. Unit tests pass.

Estimates

Please provide initial t-shirt size
M

[workato-integration]

https://new-relic.atlassian.net/browse/NR-172207

[workato-integration]

Work has been completed on this issue.