impl rate limit for xtokens

[wangjj9219]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.47518% with 46 lines in your changes are missing coverage. Please review.

Project coverage is 85.78%. Comparing base (d26b0b1) to head (c551458).

Files	Patch %	Lines
rate-limit/src/lib.rs	81.75%	25 Missing ⚠️
rate-limit/src/weights.rs	0.00%	15 Missing ⚠️
traits/src/rate_limit.rs	66.66%	4 Missing ⚠️
rate-limit/src/mock.rs	87.50%	1 Missing ⚠️
xtokens/src/lib.rs	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #854      +/-   ##
==========================================
+ Coverage   85.25%   85.78%   +0.52%     
==========================================
  Files          87       92       +5     
  Lines       10350    11055     +705     
==========================================
+ Hits         8824     9483     +659     
- Misses       1526     1572      +46     

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[zjb0807]

LGTM

[xlc]

there are some missing coverages reported by code coverage, but 100% sure if the report is correct but need to double check it

[xlc]

I don't think we need this

[wangjj9219]

If the key is AccountId, Match pattern may usually be used, but StartWith pattern can still be used to match all the pallet accounts. Can consider retaining it, and should use StartWith and EndWith with caution in actual configuration.