Any GPDB exception happens in while ORCA generating plan will abort
query.
Signed-off-by: NFoyzur Rahman <frahman@gmail.com>

This GUC will be used to control the MEMO size as well as optimization
time for large IN list or large array comparison expressions.

Only the Array with less number of elements than the GUC will be
expanded and participate in constraint derivation.

Trade-off of using this GUC is loss of potential benefits from the
constraint derivation (e.g. conflict detection, partition elimination)
with shorter optimization time and less memory utilization.

`set optimizer_join_arity_for_associativity_commutativity=7` will hint
at the optimizer to stop exploring join associativity and join
commutativity transformations when an n-ary join operator has more than
7 children during optimization, pruning quite a bit of the search space.

The 1.622 updates in b3668c40 adds
a depedency on CHint without adding the required header file to
build without warnings/errors.

This reverts commit f3134604.

Renaming optimizer_release_mdcache to a more intuitive name: optimizer_metadata_caching. Before this commit, we were caching metadata in optimizer side by setting optimizer_release_mdcache = OFF. Now, we cache metadata in optimizer side by setting optimizer_metadata_caching=ON.

ORCA uses its own metadata cache to store information about relations,
operators etc. Currently, we always reset the cache when planning a query,
unless the optimizer_release_mdcache GUC is turned off, which is slow.

To make it safe to turn optimizer_release_mdcache off, use the catalog
cache invalidation mechanism to still reset the cache when there are
changes to the catalogs that affect the metadata cache.

The ORCA-facing interface of this is the same as in the previous attempt:
A function that returns true/false indicating whether there has been any
catalog changes whatsoever since last call.

This reverts commit 6c31a3b4. Per
discussion, we will implement the same functionality in a simpler way.

Added a generation-based Metadata Versioning mechanism
which will be used by ORCA to cache and invalidate catalog
data in its Metadata Cache.
Versioning is disabled by default at this point, until the
Metadata Cache eviction policy is completed.

This commit eliminates the global new/delete overrides that were causing
compatibility problems (the Allocators.(h/cpp/inl) files have been
completely removed). The GPOS `New()` macro is retained and works the
same way, but has been renamed `GPOS_NEW()` to avoid confusion and
possible name collisions. `GPOS_NEW()` works only for allocating
singleton objects. For allocating arrays, `GPOS_NEW_ARRAY()` is
provided. Because we no longer override the global delete,
objects/arrays allocated by `GPOS_NEW()` and `GPOS_NEW_ARRAY()` must now
be deleted by the new functions `GPOS_DELETE()` and
`GPOS_DELETE_ARRAY()` respectively. All code in GPOS has been
retrofitted for these changes, but Orca and other code that depends on
GPOS should also be changed.

Note that `GPOS_NEW()` and `GPOS_NEW_ARRAY()` should both be
exception-safe and not leak memory when a constructor throws.

Closes #166