Preserve position gaps in graph phrase queries

[Incheonkirin]

match_phrase drops position holes when a token graph reaches the slop=0
phrase path with holes left by token-removing filters, for example
synonym_graph followed by stop, or nori decompounding combined with
nori_part_of_speech. Documents whose indexed positions contain the hole can
fail to match at slop 0, including documents containing the exact source
string of the query.

There are two distinct defects in MatchQueryParser:

1. createSpanQuery emits the gap one clause early. In the token loop,
   addGap for token i runs before addClause for token i-1, so the gap
   lands before the previous term instead of after it. This is the misplaced
   SpanGap visible in the _validate output of match_phrase queries miss documents containing stop words in synonyms #86021.

2. The articulation-point loop in analyzeGraphPhrase never reads
   PositionIncrementAttribute for states without a side path, and assembles
   the outer query with new SpanNearQuery(clauses, 0, true), which cannot
   carry gaps between segments. The hole is lost entirely.

Reproduction (scenario from #86021)

Index analyzer standard + stop(of), search analyzer
standard + synonym_graph("fbi, federal bureau of investigation") + stop(of).
A document containing federal bureau of investigation is indexed at
positions federal=0 bureau=1 investigation=3. Query built before this
change:

spanOr([fbi, spanNear([federal, SpanGap(:1), bureau, investigation], 0, true)])

The gap sits between federal and bureau, so both match_phrase("fbi")
and match_phrase("federal bureau of investigation") miss that document.
After this change:

spanOr([fbi, spanNear([federal, bureau, SpanGap(:1), investigation], 0, true)])

The second defect fires without synonyms, which is how I hit this. Korean
nori_tokenizer(decompound_mode=mixed) emits compound tokens
(positionLength > 1, so the stream is a graph) and nori_part_of_speech
removes particles (holes). A match_phrase query containing the exact source
text of a document then returns nothing at slop 0: for the source string
보험계약대출이율 (positions 보험계약@0(len2) 보험@0 계약@1 대출@2 율@4,
particle 이 removed at position 3), the query requires 율 adjacent to
대출 and misses the document. The new yamlRestTest in analysis-nori
covers this end to end and fails with 0 hits without this change. Raising
slop masks the bug only because analyzeGraphPhrase switches to the
finite-strings path, which preserves holes; the slop=0 span path was the only
place they were lost.

Changes

• createSpanQuery: emit the pending clause before the gap, so the gap sits
  between the correct terms.
• analyzeGraphPhrase: read the position increment of the tokens at each
  articulation state and add gaps through a SpanNearQuery.Builder for the
  outer query. The gap clauses of the built query are visited so the clause
  count accumulated during construction stays consistent with a full walk of
  the final query (AbstractQueryBuilder#toQuery asserts this).

Both changes only consume position increments that
GraphTokenStreamFiniteStrings already preserves, and align the slop=0 span
path with QueryBuilder#analyzePhrase (non-graph streams produce
"foo ? bar") and with this class's own slop>0 path.

Out of scope

When the stop filter runs before the synonym filter, the failure happens
inside the analysis chain: synonym rules cannot match across holes, and
expansions emit stop words the index never contains (LUCENE-8137). Query
construction cannot repair that. testGraphPhraseStopBeforeSynonymOutOfScope
documents this boundary and passes with and without this change.

Relates to #28838. Resolves the scenario reported in #86021 (closed as a
duplicate of #28838).

Testing

• Six new unit tests in MatchQueryBuilderTests: gap placement within, after,
  and before a side path with canned graph token streams, the match_phrase queries miss documents containing stop words in synonyms #86021 and
  Bug: When using graph synonym and stop token filter together #28838-shaped scenarios with real SynonymGraphFilter + StopFilter
  chains, and the out-of-scope boundary.
• A new yamlRestTest in analysis-nori reproducing the no-synonym case end
  to end (fails with 0 hits before the fix).
• :server:test and :plugins:analysis-nori:yamlRestTest pass with the
  change.