hotfix: Temporarily skip datagrams generated by EC150

[leewujung]

This PR includes changes to ParseEK to skip reading and saving datagrams generated by EC150 ADCP.

We can actually parse the echosounder-equivalent data fine, but we still need 2 other pieces to carry it to the next stage, so this is a "hotfix" to just skip these datagrams for now. The pieces we need are:

• determine where to save the complex or power data: as a separate Beam_group3 or with the previous Beam_group1/2?
• make sure calibration code can run through fine: not sure at the moment if all the necessary broadband calibration parameters are in place, but looks like all the necessary narrowband calibration parameters are there.

This PR still needs:

• [x] tests with small test file
• [x] an issue that document needed changes for follow-up work (#1358)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.87%. Comparing base (9f56124) to head (b34f7bb). Report is 123 commits behind head on main.

Files	Patch %	Lines
echopype/convert/parse_base.py	90.90%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1357 +/- ## ========================================== - Coverage 83.52% 78.87% -4.65% ========================================== Files 64 16 -48 Lines 5686 2708 -2978 ========================================== - Hits 4749 2136 -2613 + Misses 937 572 -365 ``` | [Flag](https://app.codecov.io/gh/OSOceanAcoustics/echopype/pull/1357/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/OSOceanAcoustics/echopype/pull/1357/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics) | `78.87% <90.90%> (-4.65%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=OSOceanAcoustics#carryforward-flags-in-the-pull-request-comment) to find out more.

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