Fix snapshot/diagnostic url parsing

[Alice-Lilith]

Description

The current version of the agent spits out tons of messages about not being able to get the diagnostics. The problem is that when you have a Kubernetes Deployment with:

env:
- name: AES_DIAGNOSTICS_URL
          value: http://edge-stack-admin.ambassador:8877/ambassador/v0/diag/?json=true

Then after you apply it, Kubernetes automatically escapes ? and = with \ characters. This prevents the current library from successfully parsing the environment variables. This updates the function that parses the environment variable struct to override these two URL member fields with manual parsing that removes any \ characters first. There are likely other public libraries that would handle this edge case correctly, and a longer-term goal I have is to remove the envonfig package from Emissary everywhere since it is incredibly over-complicated. Still, for now, this will ensure that these URLs can be correctly parsed regardless of whether they have escaped special characters or not. This was technically only impacting the diagnostics URl, but I added the same logic for the snapshots URL just in case it ever changes before we get around to removing envconfig (unlikely but possible).

Example error prior to this fix:

Error getting diagnostics from ambassador Cannot fetch diagnostics from url: http://edge-stack-admin.ambassador:8877/ambassador/v0/diag/%5C?json\\=true

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