FORK: Allow all processing commands

[ioanatia]

related: #126553

Allows all commands to be used in FORK branches.

We needed to make some adjustments to how we handle ) because otherwise using commands such as DROP in FORK branches caused errors such as:

line 4:40: token recognition error at: ')'
org.elasticsearch.xpack.esql.parser.ParsingException: line 4:40: token recognition error at: ')'
	at __randomizedtesting.SeedInfo.seed([73D239A9C4E69AD:69172FF2E651E43C]:0)
	at org.elasticsearch.xpack.esql.parser.EsqlParser$1.syntaxError(EsqlParser.java:198)
	at org.antlr.v4.runtime.ProxyErrorListener.syntaxError(ProxyErrorListener.java:41)
	at org.antlr.v4.runtime.Lexer.notifyListeners(Lexer.java:364)
	at org.antlr.v4.runtime.Lexer.nextToken(Lexer.java:144)
	at org.elasticsearch.xpack.esql.parser.EsqlParser$ParametrizedTokenSource.nextToken(EsqlParser.java:223)
	at org.antlr.v4.runtime.BufferedTokenStream.fetch(BufferedTokenStream.java:169)
	at org.antlr.v4.runtime.BufferedTokenStream.sync(BufferedTokenStream.java:152)
	at org.antlr.v4.runtime.BufferedTokenStream.consume(BufferedTokenStream.java:136)
	at org.antlr.v4.runtime.Parser.consume(Parser.java:571)
	at org.antlr.v4.runtime.Parser.match(Parser.java:205)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.identifierPattern(EsqlBaseParser.java:2254)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.qualifiedNamePattern(EsqlBaseParser.java:2056)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.qualifiedNamePatterns(EsqlBaseParser.java:2128)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.dropCommand(EsqlBaseParser.java:2849)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.processingCommand(EsqlBaseParser.java:618)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.forkSubQueryProcessingCommand(EsqlBaseParser.java:4224)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.forkSubQueryCommand(EsqlBaseParser.java:4171)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.forkSubQuery(EsqlBaseParser.java:4054)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.forkSubQueries(EsqlBaseParser.java:3994)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.forkCommand(EsqlBaseParser.java:3936)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.processingCommand(EsqlBaseParser.java:710)
	at org.elasticsearch.xpack.esql.parser.EsqlBaseParser.query(EsqlBaseParser.java:362)

@idegtiarenko provided this example to visualize the problem.
we need to make sure we pop the ) while we are still in PROJECT_MODE:

| FORK ( WHERE content:"fox" | DROP content)
^ pushMode(FORK_MODE)
       ^ pushMode(DEFAULT_MODE)
                             ^ popMode
                               ^ pushMode(PROJECT_MODE)
                                           ^ here we need to exit project mode. And also exit default mode to return to fork mode.

we needed to make these changes for all commands that can be part of FORK branches that don't use EXPRESSION_MODE (which was handled here).

[ivancea]

Looks good!

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[elasticsearchmachine]

Pinging @elastic/kibana-esql (ES|QL-ui)

[ChrisHegarty]

LGTM

[ChrisHegarty]

When we added fork initially, it was a goal to get to this point - well done!

[alex-spies]

Looks good! Only minor comments from me.

[alex-spies]

Nice test! I think it'll get stale over time - but that's not a problem as long as fork is plugged into the generative testing with other commands.