feat: allow blanket IPR disclosures

[jennifer-richards]

Fixes #7909

This adds a boolean is_blanket_disclosure field to the HolderIprDisclosure model and related forms. When set, only "Royalty Free" licensing (option "b" in section VI) is allowed. The UI for this looks like this screenshot:

Note

When "This is a blanket IPR disclosure" is selected, the form is adjusted as follows

1. the fields in V(A) are made non-required (though can still be filled in if desired)
2. the licensing option "b" in section VI is selected and other options are disabled

If the "This is a blanket IPR disclosure" checkbox is then de-selected, those changes are reverted. If a licensing option had been selected before the box was checked, it is restored to that previous value.

The text below the heading in Section IV is changed from

If an Internet-Draft or RFC includes multiple parts and it is not reasonably apparent which part of such Internet-Draft or RFC is alleged to be covered by the patent information disclosed in Section V(A) or V(B), please identify the sections of the Internet-Draft or RFC that are alleged to be so covered.

to

If an Internet-Draft or RFC includes multiple parts and it is not reasonably apparent which part of such Internet-Draft or RFC is alleged to be covered by the patent information disclosed in Section V, please identify the sections of the Internet-Draft or RFC that are alleged to be so covered.

This is a draft PR until we get confirmation that the implementation is satisfactory. We'll also need to update tests.

[jennifer-richards]

For historical context's sake, we were asked to add a reference to section 5.4.3 of RFC 8179 beside the new checkbox. With that, Section V looks like:

[codecov]

Codecov Report

Attention: Patch coverage is 96.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.84%. Comparing base (c7f6bde) to head (d7b19f0).
Report is 78 commits behind head on main.

Files with missing lines	Patch %	Lines
ietf/ipr/views.py	92.59%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7934      +/-   ##
==========================================
+ Coverage   88.78%   88.84%   +0.05%     
==========================================
  Files         296      304       +8     
  Lines       41320    41525     +205     
==========================================
+ Hits        36687    36893     +206     
+ Misses       4633     4632       -1     

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