Ensure php-fpm-exporter binary is patched

[nicksantamaria]

Motivation

The https://github.com/hipages/php-fpm_exporter project is getting patches to the master branch, but there have been no new releases in 2 years.

We want a binary that does not have 2 year old CVEs running in production.

Its been pointed out in the issue queue with no response from the maintainer - hipages/php-fpm_exporter#332

There are a few forks including one from sysdig, however none have commits as recent as this project.

Changes

• Adds a new container image called php-fpm-exporter which compiles the master branch of the git project.
• Installs the binary on the php-fpm container from the aforementioned image, rather than the 2 year old github release.

Testing

If the build passes this should be fine.

[GROwen]

Because this is going to be running along side the other pods I think it should be added to the bakefile so that builds occur at the same time as the other images. (also needs to be added to the IMAGES Actions var)

[nicksantamaria]

@GROwen sorry I knew I had forgotten something important!! Thanks, should be fixed now.