Config to allow subset of processors and exporters

[oppegard]

This adds two new job properties that let's an operator restrict the kinds of OTel processors and exporters that can be used:
allow_list.processors and allow_list.exporters. These properties are empty by default ([]), which keeps the existing behavior of allowing all processors and exporters that are included in our distribution. If not empty, then only the included components are allowed. For example, given allow_list.exporters: [otlp] and a config that contain the prometheus exporter, an error will be raised during template rendering of config.yml.erb.

Task 202 | 20:25:55 | Preparing deployment: Rendering templates (00:00:18)
                    L Error: Unable to render instance groups for deployment. Errors are:
  - Unable to render jobs for instance group 'blobstore'. Errors are:
    - Unable to render templates for job 'otel-collector'. Errors are:
      - Error filling in template 'config.yml.erb' (line 130: The following configured exporters are not allowed: ["prometheus"]. Allowed: ["otlp"].)

Given the non-GA status of the majority of OTel components, using these new properties helps limit which of the components can be used by end-users (in our case, only the OTel Collector configuration yaml of config is exposed to end-users, and we can set the new allow list properties).

We also added the memory_limiter processor in our distribution.

[ctlong]

Overall LGTM! Just a few questions and concerns.

[mkocher]

Left a few minor comments. Let's also rebase the commits and clean up the commit messages before merging this PR