feat(igxGrid): Update navigation to include ghost rows.

[skrustev]

#6640

Closes #7087

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code
• This PR includes API docs for newly added methods/properties
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes
• This PR includes behavioral changes and the feature specification has been updated with them

[MayaKirova]

Base Grid Issues:

• When there are rows pinned, navigation does not always scroll the active/selected cell in view.

  1. Run the Row Pinning sample
  2. Pin the first 3 rows.
  3. Scroll down so that "Cactus Comidas para llevar" is the last visible row (or navigate with arrow
     down until you reach it).
  4. Click the cell and hit arrow down.
     Next cell is activated/selected but is not scrolled in view.

• When some or all of the pinned rows are filtered out navigation does not skip them.

  1. Run the Row Pinning sample.
  2. Pin 2 rows - for example "Berglunds snabbköp" and "Alfreds Futterkiste".
  3. Filter so that only 1 pinned record remains (for example by "b").
  4. Start navigation from the pinned record.
     The first record in the unpinned area does not activate on the first arrow down. You need to hit arrow down again to reach the unpinned record.

[MayaKirova]

HierarchicalGrid issues:

• When parent grid has pinned rows, children active cell is not scrolled in view.
  1. Run the Row Pinning sample.
  2. Pin 3 rows in hierarchical grid sample for the parent.
  3. Scroll down parent so that bottom of child grid is visible and start navigating up in child.
     The active cells are nor scrolled in view.
     In case rows are pinned to bottom, navigate down does not scroll cell in view.

Note: This is probably due to the change in the visible view port as previously the whole tbody was used when calculation top/bottom of view port, but now view port is smaller due to the pinned rows, so calculations in _getMaxTop/_getMinBottom in hierarchical nav service should be updated accordingly.

• When child grid has rows pinned to bottom navigate down from child to parent row fails and error is thrown.

  1. Run the Row Pinning sample.
  2. Enable pinning to bottom for child.
  3. Pin a row in child.
  4. Try to navigate from the pinned row in child to the parent with arrow down.
     Error is thrown. Activation moves, but selection does not and navigation cannot continue.

• When child grid has rows pinned to bottom and navigation reaches pinned row, it is not scrolled in view (parent should scroll if child row is not visible in parent).

  1. Run the Row Pinning sample.
  2. Enable pinning to bottom for child.
  3. Pin a row in child.
  4. Navigate down with arrow down in child until reaching the pinned row.
     Pinned row cell is active/selected but is not scrolled in view.

[ChronosSF]

@zdrawku , we are done with the testing and review of the PR. Your team can go through it as well as we discussed.

[Aleksandyr]

@skrustev After some time of testing, four issues have been found:

1. After filling the whole grid view with pinned rows and try to navigate to the next unpinned row, the content starts flickering.

• Open the row pinning demos
• on the first grid fill the whole row pinning area
• and try to navigate to the unpinned one

2. Hierarchical grid: When there is enabled pinning for a particular child grid and click on a row from that child grid so that the row gets pinned through a custom template, the navigation gets frizzed because the parent tbody remains focused. (It was tried to pass the row iland through the click handler in order to select its tbody, but the value of the tbody was undefined)

3. HGrid: When enabled row pinning in a child grid and strat pinning rows one by one the selection gets wrong (two cells get selected at a time):
   

4. Unable to select a row (by space) when the selection is over a ghost element.

[ChronosSF]

@Aleksandyr , 1. is not related to pinning. I logged it separately in #7204

[skrustev]

@Aleksandyr 2 and 3 we've decided that they are sample related issues because it involves only scenarios with a templated column and will try to fix them in the demos, 4 is added to #7143 since it is not related to the navigation.