add azure linux-specific fips tests

[tobiasb-ms]

Add Azure Linux-specific tests around FIPS compliance. Specifically, this change adds:

verify_fips_is_enabled_azl: Verifies that an AZL system is in FIPS mode.
verify_fips_is_disabled_azl: Verifies that an AZL system is not in FIPS mode.
verify_fips_enable_azl: Verifies that an AZL system can be put into FIPS mode.
verify_fips_disable_azl: Verifies that an AZL system can be taken out of FIPS mode.

It also removes the AZL code from verify_fips_enable.

Due to the nature of these tests, they only make sense to run if we believe a machine is already in the correct mode. For example, verify_fips_is_enabled_azl would make sense on the marketplace image MicrosoftCBLMariner:azure-linux-3:azure-linux-3-fips:latest but not on MicrosoftCBLMariner:azure-linux-3:azure-linux-3:latest.

To accomplish this, we look at two things (see function ensure_fips_expectations).
First, we see if a variable testing_fips_image was provided to the test case. If so, and if it is yes or no, we respect that.
Second, we try to hit the azure metadata endpoint to get the image sku name. If that is a FIPS sku, we consider it to be a FIPS machine.
If neither exist, we skip the test.

[squirrelsc]

@tobiasb-ms please continue to fix errors in the PR checks.
@LiliDeng LGTM

[tobiasb-ms]

@tobiasb-ms please continue to fix errors in the PR checks.
All checks now pass.