fdf_parser.py: support `SECTION COMPRESS` sections

[apop5]

Previously, the FDF parser would fail to parse an FDF file with statements containing a SECTION COMPRESS with additional with nested sub sections.

Below is an example of a statement the parser failed to parser:

FILE RAW = <guid> {
    SECTION COMPRESS {
      SECTION RAW = $(OUTPUT_DIRECTORY)/$(TARGET)_$(TOOL_CHAIN_TAG)/FV/8C3D856A-9BE6-468E-850A-24F7A8D38E08.bin
    }
}

This PR updates the parser to be able to get past the parsing of the this, by checking there is an equal in the statement line, and pass it.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 81.39%. Comparing base (ce85203) to head (8ca0480). Report is 120 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #654 +/- ## ========================================== - Coverage 81.43% 81.39% -0.05% ========================================== Files 56 45 -11 Lines 7514 7491 -23 ========================================== - Hits 6119 6097 -22 + Misses 1395 1394 -1 ```

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