Fix #1994 (many-to-many filter in hql)

[bahusoid]

Filter doesn't work properly for many-to-many association in hql queries #1994

QueryOver generated query (works correctly):

s.QueryOver<Asset>().Fetch(SelectMode.Fetch, x => x.Documents).List<Asset>();

SELECT this_.pdoid AS pdoid1_0_1_
	,this_.IsDeleted AS isdeleted2_0_1_
	,documents2_.AssetId AS assetid1_2_3_ -- COLLECTION PERSISTER
	,document3_.pdoid AS documentid2_2_3_ -- COLLECTION PERSISTER.  REPLACED documents2_.DocumentID. In LINQ query it's still documents2_.DocumentID
	,document3_.pdoid AS pdoid1_0_0_
	,document3_.IsDeleted AS isdeleted2_0_0_
FROM Asset this_
LEFT OUTER JOIN asset_to_document documents2_ ON this_.pdoid = documents2_.AssetId
LEFT OUTER JOIN Document document3_ ON documents2_.DocumentId = document3_.pdoid
	AND document3_.IsDeleted = @p0
WHERE this_.IsDeleted = @p0

Linq/hql generated query (wrong):

s.Query<Asset>().FetchMany(x => x.Documents).ToList();

SELECT asset0_.pdoid AS pdoid1_0_0_
	,document2_.pdoid AS pdoid1_0_1_-- ENTITY PERISTER, NULL if filtered
	,asset0_.IsDeleted AS isdeleted2_0_0_
	,document2_.IsDeleted AS isdeleted2_0_1_
	,documents1_.AssetId AS assetid1_2_0__  -- COLLECTION PERSISTER
	,documents1_.DocumentId AS documentid2_2_0__  -- COLLECTION PERSISTER, NOT NULL even if filtered  so collection still tries to load filtered element
FROM Asset asset0_
LEFT OUTER JOIN asset_to_document documents1_ ON asset0_.pdoid = documents1_.AssetId
LEFT OUTER JOIN Document document2_ ON documents1_.DocumentId = document2_.pdoid
	AND document2_.IsDeleted = @p0
WHERE asset0_.IsDeleted = @p0

As you can see in QueryOver case all document related fields in select statement are only from Document table with document3 alias. And in query case documents1_.DocumentId is added from bridge table which I believe leads to this bug.

Implemented fix: substitute alias for collection persister with entity perister for filtered many-to-many collections. So documents for collection are populated from filtered entity table instead of bridge table.

Fixes #1994

[bahusoid]

Found an easy fix for this issue: do not mess with SQL generation as it's done for QueryOver/Entity Loader and instead substitute aliases for collection persister with entity persister for filtered many-to-many collection.

[hazzik]

@bahusoid I made some changes, could you please verify?

[bahusoid]

@hazzik looks good to me