Raw content return for Grid DataColumn & Column

Need to have a method  `getDataCellContent` to return raw parsed data cell content. This is useful when extending these Columns, for processing any other data before formatting via `renderDataCellContent`.
Raw content return for Grid DataColumn & Column

Need to have a method  `getDataCellContent` to return raw parsed data cell content. This is useful when extending these Columns, for processing any other data before formatting via `renderDataCellContent`.
Raw content return for Grid DataColumn & Column
Raw content return for Grid DataColumn & Column
Removed unnecessary blank space
Removed unnecessary blank space
first draft of the extension generator
WIP merge ActiveRelation into ActiveQuery

allow extending only one class to add scopes, fixes #2146

TODO:

- [ ] adjust guide docs
- [ ] adjust README files of extensions
- [ ] finish work and fix test breaks
made createQuery() config param optional
added missing use statement
merged ActiveQueryInterface and ActiveRelatioInterface
Fixes #2426: Changed URL creation method signatures to be consistent
Allow using string for URL in case there are no parameters
Allow add a condition telling the table to avoid ambiguity error.
allow configuring asset converter property with default class
updated docs about active relation
fixed absolute class links in guide
Merge pull request #2497 from yiisoft/merge-query-and-relation2

WIP merge ActiveRelation into ActiveQuery
fixed docs about AR scopes
Corrected redirect in example, used request for getting post instead of global